I have 38 of these wonderful plants growing in my backyard ranging
in height from 3' to about 8'. Some are blooming and many are ready
to. All seem to produce one just one flower, at the top of the
stem. However I have one that appears to be contrary to what the
rest of them do. This bad boy has 16 buds on it so far that appear
like they'll become flowers. None of the other plants have this.
One at the top is opening as of tonight but the rest are identical
to it, just not open - yet. There are 6 of these are near the top
where it has forked several times leaving the bud at the very end of
each of the forks. The rest are at the very end of lower branches
that already have huge leaves. Is it abnormal for a sunflower to
produce more than 1 head?

Zone 7, Albuquerque - variety is Mammoth