I suggest not reverting to the old version of AMFPHP. Solve the problem instad of ignoring it -- AMFPHP 0.5.0 simply ignores the role feature.
If you comment out the roles line from your method in the method table no authentication will be required. If you choose to keep it you'll need to write an _authenticate method. Do a search on this forum for it, I've posted two _authenticate examples.
If it's not a role problem, read this:
The latest AMFPHP version addresses the problem with the Executive.php trying to switch gateway paths, therefore fixing the multiple call problem. If you're still stumped, try the AMFPHP tutorials on sephiroth.it -- if done properly it works no matter what with the current version of AMFPHP and will help you understand better most likely.