The entropy of a single object is a meaningful concept. It is usually called Kolmogorov complexity.
The one case where they coincide (sort of) is if you believe your random sequence is generated by a randomly chosen Turing machine, which I've only really seen in philosophical settings.
A uniformly chosen 64-bit integer still has exactly 64 bits of entropy, regardless of how much Kolmogorov complexity the actual bits you generate have.