No you cannot have 2 managed server in the same cluster that belong to wls installations of different OS.
You can check the same in
"Server instances within a cluster or domain can run on any hardware and operating systems as long as the hardware and operating systems are listed on the Supported System Configurations page at
http://www.oracle.com/technetwork/middleware/ias/downloads/fusion-certification-100350.html. However, note that running clustered server instances on different hardware and operating systems may impact load balancing and performance."