Did anybody get the RAINBOW MV?

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Ugh, I feel like such an idiot. I don't understand the RAINBOW MV. It's the MV where there are two Ayumis; one Ayumi chases the other one around; the Ayumi finally catches up to the other in a café, and at the end of the MV, they're sitting at a table. A waitress comes to them, sets a glass of water on the table, and leaves. One Ayumi disappears.

I'm having a hard time understanding this video. Can you please give me your interpretation? Thanks.