Am I wrong to feel this way?

My boyfriend and I found out we’re expecting not too long ago. We are bother super happy and excited even though it wasn’t planned.

Now that it has sunk in that we’re having a baby he’s voiced that he wants to use all his 4 year old sons things from a previous relationship for this baby. (Ie: car seat, clothing, crib etc) I don’t like the idea, it just makes me feel funny, or uncomfortable maybe? I don’t know the exact emotion I guess. But he won’t back down about it. Its not like we’re hurting for money and can’t afford anything new. I also have children from a previous relationship and he doesn’t want to use the things I have for them (much newer things as my youngest just turned 1) so I just can’t understand his thought process. I need an unbiased opinion!