Well, you can. However, you have to synchronize the pumps exactly. Usually you set a timer that they pump for lets say 20min in 24h. If you set both pumps at the same time, this would work as long as they stay in sync.

I threw away the Aquabloom and bought the Gardena cordless rain barrel pump last year (with the reducer for the Micro-Drip system). It was no good for my balcony. Not enough sun and far too weak. I use the cordless pump to water all the plants on my balcony. The pressure is good everywhere (over 20 pots/flower boxes with several drippers). However, I currently operate it without a controller and simply switch the pump on when necessary.