(This is not a discussion about Gen 1 and Gen 2 connecting, but the evidence that the upper half of the Vahi did exist in Gen 1)
Ekimu refers to the upper half as "Vahi". If it never existed in Gen 1, why would it have this name? It is literally the only mask in Gen 2 with a specific name, so it must be important. Also, there were legends in Gen 1 about a mask of Time, and the Brotherhood of Makuta anticipated it by creating Voporak. However, most were unsure if could be made. Unless someone knew of the upper half, I don't see a way how the mask of time could have been anticipated. I also want to make a note of the Kratana, which have the exact same power as the upper half, which could potentially offer insight to the origins of the mask.
Anyways, why Makuta? Well, why would he want the Mask of Time so desperately? Because he wanted to connect the two halves, which I think would result in the ability to time travel.
Now, take a look at this quote from Makuta in Adventures #10: Time Trap.
"Little Toa, you have not yet begun to see even the barest outlines of my plans. I have schemes within schemes that would boggle your feeble mind. You may counter one, but there are a thousand more of which you know nothing. Even my ... setbacks ... are planned for, and so I shall win in the end."
Makuta can thank Trem Krom for knowing how to overthrow Mata-Nui, but what about his signature "Plan" that he describes in Time Trap? I think the only possible explanation is that he used the upper half to look into the future and see what would happen.
If this theory is true, that would mean Makuta has a side of him we have never seen before. How did he get the mask? Did someone give it to him? Did he craft it himself? Regardless, that would make him the only being in the entire universe, including the Great Beings, to have even held both halves of the Vahi, which is awesome.