Printing Money and Value of Savings

Say, eg, the govt printed money to double the money supply  for every 1million currently in circulation, thus making 2million, would my savings of 1million then be worth half million?

MV=PY

If National Output (Y) was constant, and if the velocity of circulation (V) was constant then printing money would cause inflation of 100% and the real value of your savings would halve.

However, it is possible that an increase in the money supply would not cause your savings to halve in value.

If National Output (Y) increased by 5% and the Money Supply increased by 8%, inflation would be 3% (roughly)

Also if there was a fall in the velocity of circulation, then an increase in the money supply would not necessarily be inflationary.

The velocity of circulation is the number of times money changes hands. In a recession, people spend less so velocity of circulation falls. This is why the US can currently increase the monetary base without causing inflation. US Money supply

So to answer your question if the money supply doubled, it is likely to cause inflation, but, not necessarily by 100% it depends on other factors