Yes, I mixed 3 brands : Hama, Perler and PhotoPearls. And also yes, the 3 brands don't melt the same way.If you like to see the beaded side (so the side that has not been ironed), then it is not a problem, because you can't see that they didn't melt the same way. But if you like the ironed side, it is a problem because some beads melt faster than others, and the piece is not that pretty.For example, here you can see the ironed side of my White Walker . I also used the 3 brands of beads. You can clearly see that the beads don't melt the same way. It was not a problem for me, because I show the beaded side instead