Ok i've found an answer by myself.
JAR FCL 1.185 (b)
http://www.jaa.nl/jar/jar/jar/jar.fcl.1.185.htm
"[(b) If the IR(A) is valid for use in single-pilot operations, the revalidation shall be completed in either multi-pilot operations or single-pilot operations. If the IR(A) is restricted] for use in multi-pilot operations only, the revalidation shall be completed in multi-pilot operations."
oh, and btw, on my licence only "IR" is indicated... no specifications of Single or Multi Pilot...( even though i know it's single pilot operations ==> including Multi Pilot Operations).