@zoom Each added strategy has access to every data - so each strategy got notified about every change in every data.
So in your case, you've added 3 datas and 3 strategies. For each data's state change all 3 strategies will be notified. That's explain the multiple 'DELAYED' events.
Regarding the proper implementation of multiple strategies, each using its own data but all of them running against same broker. There are multiple ways to implement it - and your implementation is almost right.
Each strategy may get the data name as a parameter. The strategy may then calculate the datas index using this parameter. (in your case the datas index is hardcoded inside the strategy - which is suboptimal and will not scale)