if you put a pyramid on the floor, then teleport to another map (for example cyseal->end of times), the character who left the pyramid on the floor has it back in its inventory so impossible to go back to the location where you left the pyramid by using the other pyramid

That is working as intended. You get a message about that the first time you pick up the second pyramid.

You can avoid the pyramid being put back in your inventory (for now) by placing it in a container, or leaving it with a henchman/companion not currently in your party. However, that can cause problems if you use the other pyramid on another map (you can teleport outside the level bounds, or otherwise end up somewhere you don't want to be).

ah yeah about thz trick with the container we have already had the issue with james_540