Can you equip 2 of the same equipment card to the same unit?

Yes, you can equip multiple copies of the same equipment card to the same unit.

There is no rule in Riftbound that restricts the number of equipment cards (gear) that can be attached to a single unit at the same time. As long as you have the resources to pay the Equip cost for each piece of gear and the gear is not already attached to something else (as you cannot activate the Equip ability of gear that is already attached, per Rule 730), you may attach as many as you wish.