Air carrier Captain reported receiving an airborne notification that the Captain's signed NOTOC copy was mistakenly kept by the ground personnel instead of placing the Captain's NOTOC in the aircraft's DG pouch.

Narrative

We were notified by dispatch about 1 hour into our flight that ZZZ had both copies of our NOTOC. We verified that our DG (Dangerous Goods) pouch did not contain the NOTOC. I confirmed with dispatch that we did sign it and noted the contents of the DG. He replied that he had a signed copy and could provided assistance if needed for us. He said he was going to fax a copy to ZZZ1 prior to our arrival and we followed up with them upon blocking that we had dry ice on board as well as DG.On 100% of all my flights; the load supervisor puts the NOTOC in the DG pouch. As Capt I sign both copies but also give both copies back to the supervisor. The load supervisor failed to do this and we (basic crew) failed to recognize that the NOTOC was not in the pouch. Contributing to the error is the DG pouch is aft of the cockpit bulkhead in the 747 and not visible to the crew from their seats. On future flights; I am going to add a check of the NOTOC in the DG pouch after the load supervisor departs; or designate another crew member; to prevent this from occurring again.FOM states that the NOTOC should be placed in the DG envelope and stored in the DG pouch in the cockpit. I would argue that the placement of the DG pouch is not the cockpits of our 747's therefore not easily verified that the required NOTOC is onboard. I suggest it is moved forward of the bulkhead and be located somewhere in the cockpit that is easily viewed by the crew.