I'm not quite sure, what your asking as to whether you crossed in between them or crossed from ahead/in front of them.
If I'm right in thinking it as the second one, then..
What the first person did is according to this...
The Messenger of Allah said: Pray facing a sutrah, and let no one cross in front of you while praying. If he insists, then prevent him by force because he is accompanied by shaitan. (Sahih Ibn Khuzaimah, Chapter: Salat, Hadith No. 793)
And what the second person made a mistake is he failed to follow this...
Sahl ibn Abu Hathmah narrated: The Prophet said: When one of you prays facing a sutrah he should keep close to it, and not let the devil interrupt his prayer. (Sunan Abu Dawud :: Book 2 : Hadith 695)
So, if you ask me like any other sin, while we'll be doing the sin, the devil will be accompanying us most of the time. So, as the general rule says,
Allah accepts only the repentance of those who do evil in ignorance and foolishness and repent soon afterwards; it is they to whom Allah will forgive and Allah is Ever All-Knower, All-Wise. (Qur'an 4:17)
So, it is suggested that, you ask forgiveness from God, as soon as possible in the best way you can. And try not to do it again.
May the creator guide us all.