Would fitting two different brand turbos to my RRS 2010 tdv6 make a diference to performance?

one is a hoffman turbo and the other is an OE brand turbo.

Would they be ok to put on the car or should they both be the same brand or does brand make no difference at all?

I’m not sure how the twin turbo set up in the V6 works, i.e. one turbo per bank or if like other cars (non V) has 2 turbos to give a better performance range. I wouldn’t see an issue or at least no more than having 1 new turbo and 1 well used one. As long as the spec is the same the performance should be the same. 2019 5.0 SC SVA (Current)
2012 5.0 SC AB. Sadly written off by a campervan
23 plate Focus ST (Current)
1942 VEP Ford GPW Jeep (Willys) (Current)
1943 Whites M16 Halftrack (Current)
16 plate Eurofighter Typhoon, 2 x Eurojet engines with 20,000lbs thrust each. 1380mph

Can’t answer your main question as to wether or not you can fit different brands of turbo, but the design is sequential turbos, with the second, smaller turbo, kicking in at higher revs, 2500 I believe. If you drive off fairly briskly and watch the revs you will see a significant boost as the second turbo comes in.