It's a little odd I would say. There's no shame or issue to putting your own character in the roleplay with your Gm account, especially if you do it well. I certainly wouldn't blame a GM for holding a face in with the "front line" of roleplayers. You just need to be careful not to go the "protagonist route" where your character is plainly the most important, unless that was the entire premise.

An alternate account adds unnecessary logistics in light of the above, and may present two issues. If you reveal what it is to your players, I'd anticipate the response to be along the lines of "...why?" if you never said it, and someone figured it out, there may be suspicion involved. I'd prefer you to be upfront than throw other accounts in the mix - supposedly, a different person, if you take basic steps to avoid being associated with it.