If I have Mulch's sample rate at 48k (under General Audio Settings) and Export to Sound File with a sample rate of 96k, the resulting file is twice the speed/pitch it should be.
The easy, obvious workaround is I make sure the two sample rates match when I'm doing an export.
I'm using the latest version of AM for Windows 7.
I can give more details of settings if this doesn't seem like a general bug.