Air Carrier Dispatcher reported a flight crew received conflicting Hazmat documents during preflight regarding whether Hazmat cargo had been loaded onboard. After conferencing between Captain and ground personnel; it was determined that Hazmat cargo was loaded onboard allowing flight to depart with correct documents.

Narrative

Captain called Dispatch about 20 minutes prior to departure. The First Officer was given a Dangerous Goods Form during her walk around but at the same time; a Dangerous Goods Form cancellation message was given to the Captain. In order to find out if there would be HAZMAT or not on board; I called the Manager and asked him to check the Auto-Dangerous Goods Form. The Manager called me back a few minutes later and told me that there was no HAZMAT on board which I passed along to the Captain.When the load closeout was sent; it indicated that there was HAZMAT on board so the Captain called me back to verify one way or the other if HAZMAT was on board. I called the Manager again and conferenced in the Captain. The Manager then said that the HAZMAT was on board. Fortunately; the Captain had kept the Dangerous Goods Form and after confirming the HAZMAT on board; did not have to return to the gate for the paperwork. This issue contributed with almost a one hour taxi out time and if the crew had not caught the radio closeout; the belief that there was no HAZMAT on board.Confusion began with the flight having both the Dangerous Goods Form and the Dangerous Goods Form Cancellation message. Confusion continued when we were told that there would be not HAZMAT on board. Suggestion [is to] give Dispatchers the ability to view the Auto-Dangerous Goods Form.