Looking for pre with 2 volume controls.

"I would love to hear the logic from a dealer/sales person that recommended two different mono amps.

I really think I'm missing something here."

Maybe the OP is trying to integrate a center channel into an existing system.

I've used Croft Acoustics preamps since 1987 with the two volume knobs. I guess the logic is a cleaner signal path by giving up the balance pot.
I have no problem using them.

My Mapletree Audio Linestage has individual channel gains with a single volume control. Excellent application as it allows me to set each channel gain perfectly based on room shape and contents, then control the volume overall. Best of both worlds!

If your system is passive preamp friendly I think Music First Audio has a new preamp with dual volume control, the Baby Reference V2 or something.