I busted three. Granted only 1 of them was on my pilot certificate (busted CFI-A and CFI-ME, and CPL-ME.) The last was embarassing because he busted me because I didn't have my sectional out (I knew the "flight plan" by heart by that point.) I busted the single engine CFI because at the time (and still currently to an extent) I am really crappy on eights on pylons, and it just wasn't my day on the multiengine CFI.
With all that said, I worked at the regional airlines. I got furloughed and did other work including flying freight as a UPS package feeder, and now doing the same thing for Fedex. What is interesting though is in the 5 interviews I have had with air carriers the only ones who even asked me about primary checkride failures were the regional airlines. However, they all asked if I ever busted any part 121 or 135 checkrides (which I haven't.)
I don't think you'll have a problem if you want to work for a regional airline based solely on two primary checkride failures, and if you do you probably wouldn't work at that particular airline anyway if they are unable to evaluate a candidate on anything but that. Even if on the odd chance that they decide to shun you (they won't), understand that they are the only ones who really care about primary checkride failures... pretty much due to 3407... when in fact it was part 121 checkride busts that were more compelling rather than the total number of failures.