Are you sure that it is a DA/SA and not an LEM trigger? Sure sounds like an LEM they way you describe what happens. My LEM hammer has a tiny bit of side to side play. Not much though. Maybe a millimeter each way.
Post a pic of the back end of the gun(if you can). If it has a bobbed hammer it more than likely is an LEM trigger. If it has the spur on it then I don't know.
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