use strict;
use warnings;

while (<DATA>) {

    s/(\.(\d+))(?=.*,)/$2/g;
    s/(\d+),?(\d*)/print((($1.'.'.$2)*2),"\n")/eg;

}

__DATA__

1,2
1.23,456
1.23.456,789


STDOUT:

2.4
246.912
246913.578
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