You can only enter each employee once, though. If you try to enter a single employee more than once, all of your entries for that employee will be canceled. Multiple employers can enter a single employee, however. See the next question for details.
It’s important to note that the extension is activated only when the full application is filed, not when the preliminary registration is filed. Because full H1B applications can’t be filed before April 1, if your OPT expires prior to April 1, you will not be able to get the cap-gap extension. If your OPT expires in early April, you may need to start preparing your full application before you know if you’ve been selected or not in order to be ready to file in time to get the extension. (Our lottery preparation packages include a “premium” option created for OPT holders who need to be 100% ready to file in early April.)