It may be possible.
However if you were truly "in love" with (the first man) you wouldn't have given the second man the time of day let alone found the time to spend with him in order to fall "in love".
Having said that not being "in love" but genuinely affectionately caring about more than one person is possible. However that's different from being "all in" or emotionally invested with one.
One possible exception is if you never gotten over an ex but were forced to move on after being dumped. Under this circumstance you may have built a relationship with someone new only to have your ex return seeking a reconciliation.
Even then odds are the ex still has the edge. The only reason you're with the second guy is because your breakup.