Trademarks are country specific, so USA trademarks aren't necessarily observed in other countries. Likewise, the USA doesn't necessarily respect foreign marks. If someone shows use of a trademark for product sales in the USA, then America will respect it. But sales in another country don't qualify. Also, America places precedence on first use, where many other countries respect first registrant. So that's sometimes an issue too.

There may have been a relatively recent registration in the USA for "Svetlana" by New Sensor. If unopposed for five years, it would have been hard to challenge, even if Svetlana in St. Petersburg had sold tubes with that name in the USA prior to New Sensor's registration. Svetlana St. Petersburg may not have been aware of this, and it is possible that they didn't monitor or attempt to police their name.

On the other hand, maybe New Sensor considered Svetlana St. Petersburg to be defunct. It may very well have been, and the current company may be an entirely different entirely, just using the same name, engineering and maybe some of the old fabrication tools.

I don't know any of this, it's just speculation. I'm just thinking out loud. Could have been something totally different. And I'm not expert in trademark law, that's for sure, but I have had occasion to deal with these kinds of issues a time or two. So I always kind of wondered about the two companies sharing the Svetlana name.

It's interesting to me, and I'd like to know the real story.