If you’re holding the object, your Can Pickup boolean variable is false. You need to check if that variable is true before you allow a new target to be selected (I’m assuming you’re using a line trace like the tutorial).
What I would do is keep a reference to what actor you’re currently holding. Create a new variable of type Actor called CurrentObject or something appropriate. Then, when you pick up an object, also set CurrentObject to the target actor. On the event Left Mouse Button you check Can Pickup . If it is false, then your mouse click should only drop the current object, and only if it’s true will you do a line trace for a new object.
Take a look at this screenshot. I couldn’t fully setup your scenario because my actor variable doesn’t have physics to set.
Imagine a connection between Current Object Held and Set Simulate Physics.