GPU upgrade options: considering second 5060Ti, used 7900 XTX, or RX 9700 within a $1700–$1800 budget and potential motherboard changes

Upgrade Question If we say the "budget max" is $1700-1800, and this could include upgrading to a Taichi motherboard: With a new motherboard, no need to bifurcate 1. Would you add a second 5060Ti (16GB)? Someone is...