so this is a QoL thing, I think, but it seems that the view of tank content when you hover the mouse over it needs to be above the 'filter' so it's clear which items are being delivered and which are already in the tank.
in the pictures you can see some items look like they are duplicate-delivering but in actuality the lower ones are the content and it took me a bit to figure it out - for comparison I checked the spidertron using the editor (because in my game I've not reached that far ahead yet) so here are both:
the difference is very noticeable when you ask for many items (I think I asked for 8 or 10 at the same time)