How do I make this inventory system work?

I'm making an inventory system where you can click on items (a sprite with the animation set to denote the item type) to select them, then click on a tile in the inventory to place them there. I'm running into trouble with two events which are for adding an item to the inventory and removing them from it, where they both trigger at the same time.

You can download my project here. I've left a comment above the aforementioned events.

https://mega.nz/#!awFCBZqI!2NcsbOfLjJQ9_CrJ-d177j6RTgfzCRs9Z3UBo8J8i8M

Sprite & Sprite2 are for troubleshooting - they indicate that both events are being triggered simultaneously & the pepe is the item placeholder.

Any idea how I can make this work?

I finally managed to solve this by using the 'Else' condition. I had tried it before but wasn't using it correctly. Here is the fixed project if anyone would like to learn from my mistake

https://mega.nz/#!KtF12RRQ!cSEwTnprGAEd7tkT8s5mzYFlnmGBirsUpG9Abupkcog