I keep hearing that they don't work stacked, but mine do. I'm not sure how many you can pile in one spot and have them still work. I have only done two at a time.
Whether they work stacked on top of one another currently depends on which type of Ur house you have. I don't know which is the wanted (by TS) behaviour though. So some experimenting is necessary in your R2 slash house.
if you want to save space, drop a collector, step to the end of it, and take a tiny step forward, drop another one. you will have them spaced out about <-----> this much, and that makes it easy to stop in one spot and grab all the meat from each of them.
I used 6 collectors this way and never had issues with them being too crowded or hard to grab. Just be careful not to pick it up, because you will have to move them around again to get them packed close to one another.
I have 3 collectors in my yard, all stacked in exactly the same place, and they work fine. I have 12 pigs. When I tried 4 collectors, stacked the same, the piggies got confused. I didn't realise not stacking them might make a difference.
Ohhh I didn't know this made a difference. I have 2 collectors stacked but I wondered if I can have more w/o the piggies getting confused. My yard is extended all the way. I will have to try to unstack and add another one to see what happens.
I wonder about the butterfly milkers too. Can I have more than 2 in my yard? Do they need to not be stacked too? So many things Eye Wonders about.
Mine used to work stacked, now they don't ...when I found them empty I filed a bug report, a staff member came along to my yard and told me it was because I had them stacked.. Now I separated them, they work.. :)
When you put collectors of any sort in exactly they same spot as each other, they break (unless they have silently fixed this bug in the last few days).