i agree that this is most likely unrelated to dissociation, but a great technique to use.
i use a similar technique in conjunction with dealing with alters.
for instance, one comes forward to tell/show/remake a memory, and not only do i acknowledge it, but we put it away safely together. that way the alter gets to get rid of the memory too. but it's somewhere safe where we can revisit/re-remember it if we need to. its not the same as just shoving it away and pretending it doesn't exist.
we like to picture a big wall of shiny brass locked doors of varying sizes. kind of like post office boxes.