I don't see why they couldn't use a different brand... the leather manufacturer sponsors the rider independently of the bike they ride, correct? Even then, Lorenzo and Rossi would have similar schemes to match the bike livery, but their leathers will never be the same from an appearance stance... no sense in forcing them to use the same brand.
2012 Kawasaki ZX-6R-Black
Clear Alternatives Tail Light
2005 Honda F4i-Red
2003 Yamaha Zuma-Fairy Silver
TPT 70cc Kit, Leo Vince ZX Exhaust, Malossi Delta Clutch, Scott's Damper Sticker