There is a play to trading out overpriced players.
I'm not sure you'll get 2 x $600k players, as it means your other trade out is a bit over $400k.
Trading out overpriced players generally requires:
They have a large BE, usually at least 160-170, preferably higher.
The player you trade in, in their place, can hold their own as a solid Keeper. Better than M7/8, D5/6, F5/6.
The cash it generates gets you to another Keeper in one trade.
So you are basically turning one overpriced player to 2 Keepers, with the use of 2 trades.
If you can't fit all these conditions, you probably shouldn't do it.