"Error saving file to SharePoint" (4292710)

System.Exception: Error adding document '2622a64c66d69b51802572c70023651a-010.GIF' ---> System.Exception: Error saving file to SharePoint ---> Microsoft.SharePoint.Client.ClientRequestException: The file already exists.
at Microsoft.SharePoint.Client.File.SaveBinary(ClientContext context, String serverRelativeUrl, Stream stream, String etag, Boolean overwriteIfExists, SaveBinaryCheckMode checkMode)
at Microsoft.SharePoint.Client.File.SaveBinaryDirect(ClientContext context, String serverRelativeUrl, Stream stream, Boolean overwriteIfExists)
at Quest.NSP.SharePoint.ClientSPFileCollection.Add(String name, Stream stream)
--- End of inner exception stack trace ---
at Quest.NSP.SharePoint.ClientSPFileCollection.Add(String name, Stream stream)
at Quest.NSP.SharePoint.ClientSPFileCollection.Add(String name, Stream stream, ISPUser createdBy, ISPUser modifiedBy, DateTime timeCreated, DateTime timeLastModified)
at Quest.NSP.SharePoint.SharePointDocLibraryRecordWriter.PrepareItems(ArrayList items, ISPListItemCollection spDuplicateItems)
--- End of inner exception stack trace ---