Not sure where I got the idea but it was my understanding that when you purchased a license of FileMaker Pro Advanced you could install it twice for development. I've tried this on my machine. I primarily develop in the Mac OS but test and tweak on Windows running under VMWare Fusion. If I try to leave both instances running at the same time and connect to our server I get a warning that this is not allowed and one copy will shutdown.

I'm guessing that my understanding of the two instances is wrong and the only way to do this is to purchase another copy of Advanced.

Is this correct or should I be able to run it like I had been thinking? I'm just one person on one computer in the end.

If two identically-licenced single-user copies of FileMaker Pro or Pro Advanced, whether running on the same machine or not, attempt to connect to a single FileMaker Server, the second one will not be allowed in.

I've not heard of a specific 'install it twice' rule myself, although I guess it is not completely unreasonable to install it once on Mac and once on Windows for testing purposes. But as I understand it, using them both at the same time is not allowed.

I like your signature btw -)