If you do feel something odd or not right, then I'd just replace the other rear only. Having them matched left and right should provide a perfect ride. But yeah I'd say your fine unless you feel something wrong.
'13 TiAg over Coral, 335is | DCT | Prem | L7 | Nav/Idrive | CA | 19" "-------"
A BMW is Just a Car, it doesn't make you smart, handsome, cool, or wealthy. Get over it.