While it's fine for players to possess accounts on both Natural8 and another GGNetwork site (e.g. GGPoker), there are some important rules to be aware of to avoid trouble in the future:
1. You cannot access both accounts at the same time, either on different devices or the same device.
2. You cannot enter the same event using both accounts; for example, if you play in a multi-table tournament and get knocked out, it's a serious offence to re-enter that same tournament with another account that you operate at a sister site, and will result in the forfeiture of associated winnings and the closure of the account. Similarly, multiple entries from different sites into the same event would also be a serious violation
So, with the scary stuff out of the way, it is otherwise permitted.
If there's anything else we can help with, please contact our live support or email us at firstname.lastname@example.org