It's all part of the ilok fun
By comparison K2 allows you to register on a second machine but no more than that.
Depending on how you work either way might be to your advantage. You can work on K2 simultaneously on 2 machines but would have to deauthorize one in order to use yet another machine.
M5 allows you to use it on as many machines you want but only one at a time with the dongle.
Perhaps a dongle which gave you 24 hours use after insertion would be a good compromise...?