Generating PFX is appending to the pfx rather than overwriting

[efficiondave]

On renewal, I need to generate a PFX file in addition to binding to IIS. Using the latest 2.2 version, I've set this up and it is running correctly except that it seems to be appending the new cert to the PFX file rather than overwriting the cert. This is the command line that it is running:
wacs.exe --source iis --commonname mail1.MYDOMAIN.net --siteid 2 --store certificatestore,pfxfile --pfxfilepath c:\SmarterMail\Certificates\ --installation iis

Is there something I should be doing differently? If I delete the pfx file and then run the renewal, everything is great.

[WouterTinus]

Looks like there's definitely a bug there, but not exactly the one that you described. As far as a can tell the new version is written over the previous one but without truncating the file. I.e. if the new version is smaller than the old one, you'll end up with bytes from the previous version at the end of the file. I'm not sure how resilient the average pfx parser is, but it's easy to imagine the file would fail all kinds of sanity checks in that state.