>>334633485
One toggle is likely overwriting the other. I'm assuming you set this up as two seperate ints to toggle the same material? Try set this to go off a single int parameter like: 
0 - Base mat
1 - Second mat
2 - Third mat
You'll want to do this on one FX layer.

Using two bools instead of two ints will save you parameter bits (important if you want to set up lots of different behaviours). You could instead use two bools but you will still need to set up on one layer and will have a more complex animator