Yes, there are, but in my opinion, for it to be a circular buffer, it should wrap the end of the data back round to the front when the end of the queue reaches the end of the buffer.

Inserting 4 into:

    [x, x, x, 1, 2, 3]

Produces:

    [4, x, x, 1, 2, 3]

In a circular buffer, and:

    [x, 1, 2, 3, 4, x]

In the proposed "double-ended vector". The technique is different, the amortized complexity is also different. I think therefore, it warrants a different name, to avoid confusion.