Multiple users can work on the same organisation file, however, there are a some things to be aware of:
The Budget screen auto saves, so providing you are not in exactly the same row, there should not be a problem
For other screens that have a SAVE button, if you are both in the same item there could well be a conflict on SAVE.
We suggest you have a division of responsibility across your Team, or work in Calxa at different times to ensure that work or time is not wasted.