Note that unless a card specifically says it only affects summoned allies you own, it can affect any summoned ally, including those of other players.

Place down two summon tokens of the same color with different numbers to track the two separate summons.

[Errata] Both actions should read "Up to two summoned allies"

This summon's heal ability will be performed exactly like a monster's heal ability - it will go to the ally within range (or itself) who has suffered the most damage, with a tie being decided by the players.

Place down three summon tokens of the same color with different numbers to track the three separate summons. These summons have no attack action or a base attack value. They cannot be commanded to attack with an "Attack +X" action, but they can be commanded to attack with an "Attack X" action (e.g. the Mindthief's "Possession").