In know the General Watch Co acquired the Helvetia name from Omega in 1925, but there definitely seems to be some more cross pollination. But which way, the Helvetia is from 1956: This isn't the first Helvetia I've seen with some Omega DNA. Any other Omega-a-likes out there? Connie is from felsby in the 2852 thread.
That's a tricky one really, and I want to resist the temptation to over-claim. For example, this 1958 Helvetia could be seen to resemble any number of luxury watches of the period, including Omega, but I'd need convincing it wasn't more a question of design Zeitgeist doing its thing probably.
I agree that certain styles were definitely in vogue at different times and it's no surprise that several manufacturers had similar designs out at the same time. I was just struck by just how similar my Helvetia was. And how about this one? and this one from the sales forum here a while back.