I watered and spotted an Orange chameleon in a garden and got the usual message...

Hunter watered the Blue Chameleana Flower, and spotted an Orange Chameleon feeding on the Wild Berries!

You have now spotted the Orange Chameleon 32 times in other Gardens!
4 Diamonds earned, plus a bonus Pink Diamond for spotting it in less than 5 minutes!

But then I looked at the plate and saw it has someone else's name as spotting and they commented saying they spotted it. There wasn't one on the other plate so it seems that we both spotted it!

Has anyone else had this happen to them?

Yep it happens every now and then. It has happened to me once and many others have posted on the forum that it's happened to them. It's rare but it is definitely something that happens.

This used to happen years ago in the early days of the game.Not seen it lately.

had that happen a couple months ago -- rare, but it happens

It used to happen a lot when unicorns were new, and we could only water each plant every five minutes - lots of players all madly trying to be first to water as soon as the plant was able to be watered, so it used to be quite common that more than one spotted at the same time.  Sometimes several used to be credited with the same spot.

Only one name shows because there's only space for one name but both players will be credited with the spot and get the diamonds for it.  And it means that you both spotted at the exact split second - the game counts in fractions of seconds otherwise it would be much more common.

I haven't seen it for a long time though :)

It happened to me YEARS ago, so it's nice to see that it is still a possibility.

I have not seen it happen in a LONG time, but it does happen.  You will both get the credit