Can an 18 year old male more than once during ?

We used a condom the first time and he d so much in that one, but 5 minutes later (after he removed the condom and wiped his clean), we decided to continue again without and protection.I haven't had a period in over a year due to the fact that I recently discontinued the depo provera injection because I wanted to give my body a rest from the drug.I was wondering if I could still be pregnant? I know it was a stupid mistake and I'm going to see a doctor in about a week so I can make sure the pregnancy test they give me is accurate.I'm just curious to know if a male can twice in one session? The second time there was no sperm even present.He said he felt like he was going to ejaculate, but when we stopped to check, there was nothing there.Can anyone explain this to me? The first time he ejaculated there was a huge amount of semen in the condom and 5 minutes after that he said he was going to ejaculate?Is that possible?