If you are flying different types (which is limited now by authorities, under commercial operations, the number of type ratings on complex helicopters is limited to anything up to 3 types only), the seats need to be changed not on every opc, but on every other opc on that type.
January Type 1 left seat
March Type 2 Left seat
July Type 1 right seat
September Type 2 right seat
For example.
That is IF the pilot is required to operate from each seat, which should only be the case for certain long line operations or while flying with PICUS/Line Training without being an instructor...
Instructors will be qualified to fly Pic from the left seat anyway....