I'm like that, except for those things I can do both ways, because it's useful and sometimes necessary - like using a shovel. There are a bunch of things I only do with either the left hand only, or the right hand only. A right-handed friend always throw balls with his left hand. Most other things he does with his right hand.

I'm right-handed. I'm definitely sure of that. It's just that what hand I use depends on which hand I start with from the beginning. And that'll be the preferred hand, except for things where it's natural to switch from the very beginning.

But there are also some things I've learned to do with both hands much later, e.g. washing dishes - there was a reason for having to do that for a while, and now I just switch when I like it, or if the kitchen happens to be arranged in a way which makes one side more preferable.

(BTW, when building carpenters still used common hammers it was completely normal to use either hand, as access space may be limited and there's basically no choice sometimes.)