No, they are different filters. The
DGM is much tighter in band through pass than the
Omega OIII Hb. Specs are distinct. But if I am mistaken, I am happy to be shown otherwise. I don't see where you say you've had an Omega OIII Hb filter, unless it is through the initial suggestion that these two filters were the same one. I also mentioned the Omega ownership of DGM in post No 3 of this thread, first paragraph.
I'll search out some other mentionings of the DGM OIII filter - if I remember correctly, it too is highly regarded as one of the best OIII filters on the market.