It's all in the title but to go further in to detail, my friend, Cristal Pink and I won 2 Magma cube spawners from the vote creates but when we placed them down in the nether they turned into regular pig spawners. I was able to pick them up with my silk touch pickaxe hoping they'd turn back into magma cube spawners but they both remained pig spawners...
I think this is a current glitch for magma cube spawners, as other people have also experienced this. It could be a database error, or just a faulty plugin, but I'll put it on my list.