In the UK, the IR is type specific but it is the initial IR which the twin operator will be looking for and that could be on any twin helicopter. For instance, you will not be expected to have to pay for your own Super Puma IR before a NS company will employ you .
If you are offered a job, the operator would likely provide you with a conversion course which would include a IR on the new type. This would more than likely be covered by a bonding agreement.