If I have two Gem Crafters on the battlefield, does the ability trigger twice when a new unit enters?

Ruling: Yes, if you have two Gem Crafters on the battlefield, the ability triggers twice when a new unit enters. Multiple instances of Vision trigger separately.

Sequence:

• When a new unit enters, the first Gem Crafter's Vision triggers
• Look at 1 card and decide whether to put it into your memory
• Then the second Gem Crafter's Vision triggers
• Look at 1 card and decide whether to put it into your memory

Nuances:

• When you play the second Gem Crafter, it will also trigger both existing Gem Crafters' abilities
• You resolve each Vision trigger separately (look at 1, decide, then look at the next 1, decide) - not look at 2 cards and decide for both at once