Yeah, that's definitely not true. I've never even heard that before. But there is no logo drawn on any part of the manga series that says "Dragon Ball Z" or "Dragon Ball 2." The logo reads simply "Dragon Ball" all the way through to the last chapter of the series.

Now, the rumor I heard is that Toei came to Toriyama or Toriyama somehow heard that Toei was planning to relaunch its own series and suggested the Z himself as a rather tongue-in-cheek way of getting people to think that it was almost over.