Folder - duplicate documents weird behaviour

I have folder A and B, doc after process moves from A to B.

I wrote script to move document from one folder to another, used following script.

Call doc.PutInFolder(FolderName,True )

Call doc.RemoveFromFolder(currentFolder)

putinfolder working fine, but Remove from folder removing document instantly, but appearing again in same folder after sometime (now doc appears in both folders A and B). Softdeletions are disabled on db.

Why this weird behaviour taking place? Is there any way I can hide duplicate doc in folder B?

Thanks