We're getting married next year and thinking of writing our own vows if we do, do the bride and groom write different ones to eachother or do they still have matching ones?

That is entirely up to you.  YOU are making the vow .. So articulate what YOU want to promise

It is your wedding and you can do whichever you wish. I will say most that I have seen wrote separate vows. But I liked the ones that were similar and personal.

That's the beauty of writing your own vows.  You can say exactly what's on your heart .... Matching or individually unique.  Congrats!