Grow plants separately just incase?

I planted a bag seed about 6/7 weeks ago so I've no clue what it is. (Total newbie). I planted a seed this week that I know is female because I bought it. So my question is
Should I keep them separate until I know if the first one is male or female?

You can keep them together until they show sex. The pollen sacks take a while to mature so nothing will be pollinated for a while even when you can see them. So check regularly and you will be fine.