Do different tires front/back damage LR AWD mechanics?

I'm looking to get into a D1, and found one that appears to be in decent condition locally and that I can afford. The main gripe I have so far is that the seller has been driving it with "old" and "new" tires in front vs back, and although they are the same overall tire size, they are different brand tires. I'm more familiar with Audi Quattros, where this is a big no no. Not familiar with the LR Disco AWD mechanics.

Would this tire setup damage anything?

A D1 has enough grit to put up with new and old tires of the same size although I don't recommend it.
I doubt any damage has been done but as part of buying a used vehicle I always suggest you replace all the fluids, so while changin out the diffs and t/case just keep an eye on the quality of the gears oil and any indications of water or meatl shavings.
If you buy the truck, what are your plans for it, what size tires will you install?
Mike

It's a second car intended for Colorado trails and winters like the past two months. Budget is a factor right now so nothing that requires a lift, but I plan to look into offroad mods since I'm looking to hold a nice D1 indefinitely.

What are good affordable offroad tires for the stock 16" wheels with the stock suspension?

Are you in Colo? if so call me in Parker and we can talk.
Mike
303-862-7680