If you for some reason are quite keen on focusing on riding twintips, which is understandable just like I prefer to ride directionals now, having two regular shaped TTs makes a lot of sense.
One for really powered conditions where you can edge even more and cut through heavy chop, and because of being powered going upwind is not an issue, and when landing hugely powered kiteloops they land smoother even if "you" dont so to speak, and a smaller board feels more agile too.
And then a wider one, maybe or maybe not a bit longer, maybe or maybe not a bit more flat, for normal winds and overall general riding
An advantage could be, that if winds change a bit you can just jump in on the beach and take the other board - a luxury one will appreciate very fast, opposed to rigging another kite size
It is a lot easier to have only one TT nowadays IMO, as in the early days the smaller ones were a lot better and didnt feel clumsy like the bigger ones - but today where they are wider and not longer and shaped well, the wider ones can work in all conditions except light/marginal winds, so you dont need two TTs like back then.
But you might still find the benefits of the "smaller" one you havent got yet, appealing.
Unfortunately I think there is only one way for you to find out
Personally I like to have several quite equal boards, with some slight differences, instead of very different boards.