Here's a good advanced technique that will save you from being a part of a double posting costly crash.
First - if you aren't following
@xivarmy suggestion, do that immediately and enforce it. COMMUNICATE in the topic first that you're taking something, THEN venture out and take it.
If you can't get that to really take hold in your 1.9, then until it does - protect yourself.
If you call a position and begin to take it (but aren't sure someone else isn't doing the same thing....)
place ONLY 1 FP of your investment into the building.
That 1 FP is sent to the service @ Inno, and it's put into the list of people on the building. THE RESULTS are then sent back to your screen.
If someone else took the slot, you'll see it immediately, because a service update was done, and that's your goal. It's the same as exiting the topic, or even the game (which is pretty drastic to get a service update...).
If you don't see anyone else, and it comes back clean - its probably such that YOU OWN the position you called in the 1.9 topic, and you can put the remainder of the FP due.
The 1 FP "tickle" FORCES the service to reconcile ALL investment and give you the absolutely latest amounts from EVERYONE - including hoodies, friends, etc.
It FORCES that to happen - so you can see who's on the building.