I don't see what is wrong. I made this example now: https://fxdreema.com/shared/3BN8jwtV
Test this on M1. In Block 6 I selected M15, so a new random trade is created ever 15 minutes. I set expiration time for the Buy trade to be 10 minutes and for the Sell trade to be 20 minutes... so we can have different situations.
If the last detected trade is Buy - white arrow is printed. If the last trade is Sell - red arrow is printed.
Both "Draw Arrow" blocks can draw one new arrow on every run and that's how I want to check whether or not "check type" passes twice on a run. You see this "Once per bar" (block 10) above that allows the loop blocks to run only once per bar, so in the ideal situation we would see 1 arrow per bar. You can connect the other "Once per bar" (block 11) to see that you will start to see 2 arrows per bar... well, arrows overlap actually, so you have to move one around to see the one below.
I checked this and I see no problems for now. Here is a screenshot:
0_1533233453985_01386031-a36d-47bb-9403-fa66f70ae016-image.png