You'll notice very few people use their real names on FlyerTalk as their handle. Now you're starting to learn why.

You can change your FT username. It will still show your old user name for a while (I'm not sure how long), but that'll be in small type, so much less noticeable.

As to how many people? Keep in mind that AA's charts at gates for upgrades and standbys is just the first three letters of the last name and the first letter of the first name. There's apparentlly little enough duplication in those 4 letters on a given flight that they've never felt the need to use anything more than those 4 letters.