Last Updated: September 11, 2014
Yes, you can synchronize models from the same model family: For example, the HD1020 can be synced with the HD220, or the 4K242 with the 4K1142.
However, you cannot synchronize models from different model families: For example, the XD230 cannot be synced with the XD232 or HD220.
Players must be synchronized over an Ethernet connection (not WiFI). You can synchronize two units by connecting them directly to each other using a standard Ethernet cable; for any larger deployments, you will need LAN infrastructure.
See this FAQ for more information on using synchronization.