No, SIG Panama 2012 cannot open SIG files, the fact that they have identical names is purely a coincidence. As far as I know, the SIG format is a signature text that's usually attached to the end of emails or business-related documents, while the application that you're asking about is a map viewer.
According to online sources, in order to open SIG files, you will need an application like PrintMaster Gold or The Print Shop.
