You're diversifying for sure.
However, I'm not sure whether or not it's necessarily a good idea to invest in two coins that are completely opposites of each other. That could potentially mean that any gains in one of the coins can be offset by losses in another coin in your portfolio. I'd rather pick a sector which I think has potential and diversify within that sector.
This one. The first thing that comes to my mind is the baccarat table, you can't beat on both banker and player, so it will simply negate each other.
Also, you're not completely eliminating the risk that one of the projects will go rogue. This indiosyncratic risk will always be there.
So if we are talking about diversification here, better go to stocks or precious metal. It's hard to invest on altcoin nowadays and as much as we love to see that website with the correlation thingy, I doubt that it will be very much effective in the long run, just saying.