Munchkin Fu unresolved combat

[Kroony]

When Opening the door i revealed a Level 2 Fox Spirit. I was on level nine so beating it wins me the game.

I was comfortably beating it when someone played 'Spirit Mirror'
"Play during any combat to make one monster friendly. it cannot be slain, so it is worth no levels. The munchkins fighting it will get its treasure unless they flee from other monsters in the same combat. Usable once only."

I retorted with 'Stunt Double'
"Play during any combat. Another monster appears, of the same Level and with all the same bonused. If the monsters are defeated, draw treasure for each and go up levels for each. If player flees, he is at -1 to Run Away."


So my question, is the Spirit Mirror considered a Bonus and effective on the new monster. Thus meaning all i did was double my treasure? (which by the way was removed through a -5 to level of monster card!) Or cause the Spirit Mirrors only effects one monster, can i still defeat the 2nd and win the game?

Your thoughts would be greatly appreciated