Hi,
thanks for this report - Indeed (and that means I can confirm) it´s a little bit strange all the different values from one and the same database 
I have tried to find out why this happen now because I was also curious.
This VORDME (MGA) what you have found is really special because the range/power is “unknown” and therefore everyone define it in another way. We define VHF navaids, which have no official classification (=unknown) as LOW VHFNavaids with 125Nm. The LNM developer defines the same navaid as LOW with 40Nm - he is also using our database as basis and therefore he came to the same result, that MGA has no power/range indicator and therefore he set all these VHF navaids to his default LOW/40Nm.
We will change this in the near future for MSFS. In the near future, all “unknown” VHF navaids will be “HIGH” with a range up to 130Nm.
Cheers,
Richard