Don't want to nitpick on that, but this statement is only true if we are talking about the value of the exponents.

If we are referring to the resulting values of 2 raised to the power of 64 and 128, then it is incorrect to say that the latter is only twice as much as the former. The difference is actually much larger:

2 ** 64 = 18446744073709551616

2 ** 128 = 340282366920938463463374607431768211456