According to my readings and understanding MGTRE is your right...

According to my readings and understanding MGTRE is your right to buy MGT shares at $0.025 via the acceptance form. (you should see this on your acceptance form)
So if you have 10,000 MGTRE rights, that means you can apply for 10,000 MGT shares for $250.00 via the acceptance form.
This will also entitle you to 5,000 options, which you'll get in addition to the 10,000 MGT shares.

If you purchase an extra 20,000 MGTRE rights at say $0.007 each on market, you'll now have an accumulated total of 30,000 rights.
This gives you the right to apply for 30,000 MGT shares for $750.00 via the acceptance form.
You'll also get 15,000 options in addition to the 30,000 MGT shares.

Hope this helps, and I hope I've got this right.

You should check and confirm with your broker or financial adviser before making an investment decision.