Quote from DT-waw:
Well, it does make sense. Let me outline a simple example:
1st model opens LONG position at 1.2970, 2nd model opens SHORT position at 1.2970. Now, 1st model has a stop-loss at 1.2940.
When the price will reach 1.2940, 1st model will close LONG position BUT 2nd model will still hold open SHORT position.
If I'd net both positions or if I wouldn't open any -due to opposite sides or signals, I wouldn't have a 1 SHORT position below 1.2940 level.
I can have opposite positions on multiple accounts with Oanda, why I can't have them with IB?
DT-Waw
We probably should implement this as we would get double commissions!

But lets break this down...
This is what you want do do:
Model 1: buys 1 at 1.2970. Places sell stop at 1.2940
Model 2: sells 1 at 1.2970
Now, your stop triggers at 1.2940.
This leaves you short 1 at 1.2970 from Model 2.
Total number of trades = 3
This would be the same as doing absolutely nothing when they both give opposing signals.
Placing a sell stop at 1.2940.
Then when we trade though 1.2940 stop is triggered and you are short 1.
Total number of trades = 1
Other brokers allow you to do it because it encourages trading, but it's a con. Instead of having a flat position, you have 2 open positions in the market... which you will need to trade out of.