Q:

Will a copy of a flashed-back Increasing Vengeance still make two copies?

Increasing Vengeance says

Copy target instant or sorcery spell you control. If Increasing Vengeance was cast from a graveyard, copy that spell twice instead. You may choose new targets for the copies.

If I flash back an Increasing Vengeance, and then I copy it (possibly with another increasing Vengeance) does the copy still make two copies, or does it only make one because spell copies aren't cast?

A:

No, it will not make 2 copies. See the ruling on Increasing Vengeance. 

When Increasing Vengeance resolves, it creates one or two copies of a spell. You control each of the copies. Those copies are created on the stack, so they're not "cast." Abilities that trigger when a player casts a spell won't trigger. The copies will then resolve like normal spells, after players get a chance to cast spells and activate abilities.

The copies were not cast from the graveyard, so the replacement effect doesn't apply. 

