Under EASA SE-IR and ME-IR are to different ratings.
If you had an JAA license you would have grandfather rights for the SE-IR if you hold a ME-IR. If you have EASA license by just doing the ME-IR skills test you would only be allowed to fly ME in IMC, you would have to do a SE-IR skills test to do so on a SE.
If you do a ME-IR with 3 approaches you can use that to cross-credit for your SE-IR. Assuming you still had a valid SE-IR