MMSI for my new radio

I just got a backup HX870 and I need to enter this MMSI. I looked in my email records and I have an old one I used for my other radio.
Can I use the same one twice? It says not to make any mistakes, otherwise it needs to be sent back to the factory.

Any ideas? It looks like a new one is $25.
Thanks.
-Andrew

Never mind. I went to seatow.com and figured it out.