Strange result with nextUp for reals

[Andrej Mitrovic]

-----
import std.math;
import std.stdio;

void main()
{
    writefln("nextUp of %a is %a", 1.0, 1.0.nextUp());

    real num = 1.0;
    writefln("nextUp of %a is %a", num, num.nextUp());
}
-----

This prints:

nextUp of 0x1p+0 is 0x1.0000000000001p+0
nextUp of 0x1p+0 is 0x1.0000000000000002p+0

Any idea why the results are different?