All that the linked example demonstrates is that there's a discrepancy in the %.20g formatting - it says nothing about the ability to assign values correctly.
If you compare the actual values by doing "%a" formatting on both the Linux and windows perls, you'll see that 0.1 is exactly the same double.
Also, I believe the OP's activestate perl was built with (mingw port of) gcc. They stopped using Microsoft compilers a few years ago.