Mirror-Shield Hoplite

If a creature other than the creature with backup ends up as the target of both the backup ability and the copy, it will end up with two +1/+1 counters and it will gain the non-backup abilities twice. In some cases, the duplicate abilities will be redundant (two instances of flying, for example). However, if it picks up two triggered abilities, for example, those abilities trigger independently.

The source of the copy is the same as the source of the original backup ability. If the creature that ends up as the target of the copy is that original creature with backup, it will get a +1/+1 counter, but it won’t gain any abilities. If it’s a creature other than that original creature, it will get a +1/+1 counter and gain abilities.

If a backup ability causes another creature to gain abilities, the creature with backup will still have those abilities.