It's likely the same plant ( mine does clump) but you can still split them (i would not), just make sure each plantlet has its own roots and let dry the root you cut to separate them before replanting.

It looks like two clumps. They are planted too deeply. They should be at the level they were in the nursery pot.

^^ I agree. At least two separate plants and too deeply planted.

So, should I leave the 2 plants or cut one of them down?

What do you mean by "cut one of them down" ?

I agree with the others, they are planted too deep.

If were me I would dig them up, separate them and replant spaced apart.

Remove one plant if you want fewer flowers.

I'll just leave it and see how it does. I was worried 2 plants would out-compete each other but the roots are intertwined with each other so it would be very difficult to separate them. That's why I was thinking of cutting one down to ground level but I think I'll leave it. I'll double check the planting depth too but I think it's just the angle the picture was taken.