For the BMW Mini, ZF Services UK recommends replacing shock absorbers in pairs and also fitting new service kits.
Shock absorbers should always be replaced in pairs to optimise vehicle handling. Fitting new shock absorber service kits (bump stop/dust cover) at the same time is recommended, as the old bump stop may house grit that could damage the piston rod of the new shock absorber. This could lead to failure of the top seal of the new unit, causing it to leak.
It’s important to cross reference replacement parts with original equipment (OE) part numbers to ensure that correct specification shock absorbers are fitted, and to use correct tooling when mounting the shock absorber – never use gripping tools on the piston rod.