Do plants always have just one apical meristem at any given time? If I see multiple buds at a shoot tip (multiple "apical buds"?), what am I looking at? Is it:

1. multiple ("codominant") apical meristems, or
2. the buds compete for dominance until one of them ends up being the apical meristem, or 
3. one of the buds is the apical meristem & the others are axillary buds pressed up really close to it?

Thanks!

I think plants always have more than one apical meristem at any given time. They exist at the tips of shoots and of roots.

If you have a branching tree (think 'oak') then you have apical meristem at the tip of each branch and the roots.

If you have a single trunk (think 'larch') then you have apical meristem at the tip of the trunk and the roots.

It has been a while since I studied this so take my comments with a grain of salt.

Thanks Zapatos! And I now see that I should have clarified my question: I was refering to a single shoot. It sounds from what you wrote that you think there'll always be just one apical meristem at the tip of any given shoot (i.e. that even if I think I'm seeing multiple buds at the tip of a shoot, only one of them is actually the apical meristem), correct?

That's correct. There is only one apical meristem at the end of the shoot. Other things you see at the end would be newly forming leaves, axillary buds, etc.