Games : Is there a narrative reason why Majora's Mask reuses so many art assets?

The Legend of Zelda: Majora's Mask reuses many art assets (including NPC models) from Ocarina of Time. Is any narrative explanation ever given for this? For example, is the game a dream or an alternate dimension or anything like that, which would explain why the same person has a different name in the sequel?

To clarify: I understand that in the "real world", this was done to speed up development. I'm just trying to remember if they ever tried to explain it away within the narrative.

I found a quote from Zelda Wiki about reasons for reusing assets:

Eiji Aonuma, a key developer of the game, had stated that reusing many aspects of Ocarina of Time allowed his team to program the game in less than two years (as Ocarina of Time took no less than four years of development).

But I can't find anything about a narrative reason.