DVM is correct. Many companies bought tubes from the major manufactures at the time and relabeled them with their own logos.

To muddy the waters even further, major manufacturers of the time would buy tubes from each other rather than tool up for a new run of tubes. I have RCA-labeled tubes marked G.E., for example.

The tube in the photo looks like a GE to me. Are there seven little dots etched into the glass below the "12AT7?" If so, then it was made by G.E.