Example:
A: Hey, I just bought a mouse.
B: A mouse mouse? Or a computer mouse?
What is this exactly? And are there any rules?
Example:
A: Hey, I just bought a mouse.
B: A mouse mouse? Or a computer mouse?
What is this exactly? And are there any rules?
This is a kind of retronym. It has been called contrastive focus reduplication.
Rhetorically, there is, by implication, a combination of synecdoche and metonymy involved in the "mouse mouse" locution.
These two figures of speech involve part-to-whole relationships and/or the substitution of parts-to-whole relationships.
All hands on deck [implied is "the deck of the ship"]
is metonymic because the word hands is a substitute for the word sailors. Yes, hands are part and parcel of sailors' bodies, but those hands are also, synecdochally, parts of a whole.
"Mouse mouse," then, means in essence "a real mouse" (or perhaps more accurately, a "live mouse" or a "flesh and blood mouse"). Just as a computer mouse imitates a real mouse by being small, having a "tail" (if it's a wired mouse, that is), and moving around the mouse pad in little and quick movements, so also does the real mouse by virtue of being small, having a tail, and moving about in little and quick movements, correspond synecdochally to the faux (computer) mouse.
This inter-correspondence or analogical similarity of features is at the heart of the way the synecdoche/metonymy figure is employed in the "mouse mouse" locution.
This is an instance of 'noun as adjective'. The usage is explained in the article quoted below in some detail.
The important point is that there is no difference in grammar between 'mouse mouse' and 'computer mouse'. In both cases a noun is used to qualify another noun. You can think of it as a coincidence that the first phrase uses the same word twice.
The reason for this usage is that computer mice are more commonly found in most houses now than are real mice. That represents a big change in our language--before personal computers, the reverse was true.
That said, there is an element of humour involved and the repetition sounds 'cute'. It would have been clearer to say, "A house mouse or a computer mouse?".
Comment
There is unlikely to be a phrase covering this specific use of a repeated word (in my opinion) because the phenomenon that gave rise to it is very rare or even unique. Maybe someone will prove me wrong with other examples.
Noun as Adjective
Sometimes we use a noun to describe another noun. In that case, the first noun "acts as" an adjective... The "noun as adjective" always comes first...