1 Campaign, 2 Parties, 3 SAME PLAYERS.
 

For Simplicity sake, each letter is a specific player, and each number connected to the letter is a specific character they played. There are 3 players, A, B and C.

Campaign started with
A1, B1 and C1.

As of now, we have are
A2, B1 and C2

A1 died and C1 ended up separated from the group.

Thing is A1 will be resurrected, and instead of discarding A2 or finishing his character arc too abruptly (which would be understandable, but still bad for the story) I thought of separating these PCs into GROUPS (Allowing them to fully play PCs they couldn’t do before is also a major reason).

GROUP 1:
A1, B1, C2

GROUP 2:
A2, B2 (new character), C1

The Setting is an enormous megadungeon overlapped by various systems of caves, it connects the world, meaning it’s an incredibly fast way of traveling, but dangerous.
This is essentially gming the same campaign for two tables of the same people, and some events taken in a group may affect the other.

A SESSION would be EITHER of GROUP 1 OR of GROUP 2, players would NEVER PLAY 2 PCs AT THE SAME TIME.
The campaign will be basically over by when they reunite.

What I need are insights. Mostly on concerns I should have in mind and opportunities it gives.

I have intention of limiting communications between GROUPS 1 and 2.
The players are aware that they will control 2 PCs in different places. I told them a year ago.
Medieval High Fantasy, TL3.

Re: 1 Campaign, 2 Parties, 3 SAME PLAYERS.
 

I ran a multi-year fantasy campaign where each player controlled 2 characters. The characters communicated with each other and each player could choose which character to take on each adventure.

It was a dungeon-delving, diplomacy, and mass army battles game, so there were roughly two teams: the generals and diplomats team, and the dungeon delvers. But both teams got caught up in situations where they had to fight mass battles, negotiate treaties, or explore dungeons, and membership of each team varied a bit and characters sometimes moved between teams briefly.

I hadn't intended for each player to control 2 characters, but my players insisted and it worked pretty well. So I think what you're doing has merit and can work.

You have two entirely independent groups with fixed membership, so it should mostly be a pretty standard experience. As you said, you're running the same campaign for two different groups that just happen to have the same players.

The only thing I'd recommend is subtly providing different views of the same information to the two groups. If group 1 knows they're next to Grimtooth Mountain, group 2's maps should have Grimtooth Mountain in the wrong location, so if they set out for it, they still have an appropriately hard times reaching group 1.

Re: 1 Campaign, 2 Parties, 3 SAME PLAYERS.
 

DARK SUN would have something like that, where each player controlled four (three?) different character and would choose who would do what.

Re: 1 Campaign, 2 Parties, 3 SAME PLAYERS.
 

Some players can have problems keeping knowledge that char #1 has separate from knowledge that char #2 has. When you start a session, do a good 5 minute rehash of what the characters being ran know and did last.

Remind the players when the 2nd group of characters start an engagement with an opponent that the 1st group of characters already dealt with that this group doesn't benefit from the other group's knowledge. It IS possible that an opponent might learn from a non fatal encounter with group 1 and use that knowledge if it encounters group 2.

Make sure you as the GM keep good notes on which group encounters what opponents and the outcome. If group 1 kills an opponent, then group 2 shouldn't encounter the same opponent.

Re: 1 Campaign, 2 Parties, 3 SAME PLAYERS.
 

Someone who is well known in the RPing community famously said that to have a meaningful campaign, strict recordkeeping of the passage of time is essential. I think you will have to be careful on that matter

Re: 1 Campaign, 2 Parties, 3 SAME PLAYERS.
 

A friend ran a Star Trek game once where every player had two characters; one bridge, one support. It let us have a variety of options for away missions and requests for help from the ship.

Re: 1 Campaign, 2 Parties, 3 SAME PLAYERS.
 

That seems to be an important factor here. I was planning on handling it mostly cinematically, with some moments in mind as “the party is finally getting to the same location” ending in them discovering the other had left it already, that could be dangerous as a “rail-road: you obligated them to leave” but honestly I there can be a situation where staying doesn’t make sense or its better to leave.

I perhaps will keep track of time, I’m using FANTASY CALENDAR, so that should be smooth.

Re: 1 Campaign, 2 Parties, 3 SAME PLAYERS.
 

I'm also reminded of Ars Magicka, where (if memory serves) everyone has a wizard character and a mundane character. Since wizards in that setting spend months on end poring over books in dusty libraries, adventures are generally expected to involve a few wizards and several bodyguards, wilderness guides, etc. (i.e. a pretty typical fantasy adventuring party).

Re: 1 Campaign, 2 Parties, 3 SAME PLAYERS.
 

I take part in a Cinematic Fantasy Setting which is one of several Setting that my group uses. The group has 5 players, 3 of which regularly GM with the other 2 doing so once in a while.

The Sapphire Setting has been active for about 30 years. Over the years 5 groups of PCs developed (Borderlands, City, Darkgard, Thieves and Mages). Each player has at least 7 Characters which are spread among the groups. Three of these groups have always mostly operated in the Capital (Sapphire). All PCs have now arrived in /returened to the capital. In game elapsed time is 1year and 10 months.

With Multiple PCs per Player keeping close track of the Time is very important because some scenarios may overlap and it keeps it clear what PC is not available.

We allow players to Play 2 PCs at same time but that is very rare. Communication between PCs in different 'groups' is allowed and is played out as needed. If both have same player what is passed is clearly labeled.

Since they are in same city the mix of PCs in a scenario depends on what the scenario involves.

Our group has (through practice) become pretty good at keeping information limited to the PCs who would logically have it. I think it is pretty important to make sure of this. It has become easier for us to do with practice.

For a long time each group was kept pretty separate and the PCs would vary only to the Players PCs in that group for the scenario. Several years ago we began going beyond 1 group for getting a PC for the scenario. It was fun before mixing but the cross mixing just made it better by adding new twists to the interactions.

Bobby

Re: 1 Campaign, 2 Parties, 3 SAME PLAYERS.
 

If you really want to have two separate groups, that should be fine with sufficient record keeping and/or mechanically connecting any PCs where it would be appropriate. B2 is gonna be a new character, so if they want to come up with something that connects them to B1. Like the classic mental link (be it psychic, magic, spiritual, etc.) between two twins. Otherwise, yeah, players need to be able to compartmentalize and not take advantage of what they know that their character's don't.

However, my old high school gaming group (back under Third Edition, Revised) had session where almost everyone had invited a new player. They were totally new, so right or wrong I think most of us also built a character for them to pilot, at least for the first session...

...none of them showed up. The GM had planned an adventure for a larger group with the new characters, so he asked if we wanted to run a second character. We did, and it was fun. Yeah, we had to be cautious not to unduly favor our pairs of characters or act upon information we didn't have... which was easier than it sounds. Instead of separating our two characters, we just often paired and either roleplayed them already having a (mundane) connection or developing one quickly.

Anyone who already had an handle on GURPS, would run two characters. When newer players joined the group who were learning GURPS, we only had them start with one character, and the option to bring in another later. We had more than one GM in our group, running different campaigns, and we ended up running multiple characters in a WEG Star Wars campaign, as well as another GURPS (Third Edition, Revised) game.

Yes, it can and will create some problems, but at least as a player, I found it to be worthwhile.