One-taped RAM vs Multi-taped RAM In Turing Machine, we know that there's (fine-grained complexity) difference between one-tape, 2-taped and multi-taped TM, even though they could be simulated efficiently.

(Well, actually I'm not quite sure they are indeed seperated: i.e. $TIME(t)\neq TIME_{2-taped}(t)\neq TIME_{multi-taped}(t)$ )

But today I'd like to focus on RAM model, is there any complexity seperation between one-taped RAM model and multi-taped model? Though we might expect it be quite small because of random accessibility.
Random-access machines support the following operation in constant time:
$$
x \gets M[y],
$$
where $M$ is the memory array, and $y$ is an index whose allowable size depends on the exact model. Whether $M$ is an array of bits or an array of words depends on your exact model.

If you had several different memory arrays, say $M_1[y],\ldots,M_r[y]$, then you could simulate the command
$$
x \gets M_i[y]
$$
with the command
$$
x \gets M[ry + i]
$$
which also takes constant time.

Therefore there is nothing to be gained by allowing several "memories".