The problem is when both pass the test Close (0)/Close(200)>=1. In this case the screener will buy both, which is not what you want (I think). If you only want to buy one, you need to decide on a ranking function, then in the backtest screen set the “No. Top Stocks” field to 1.
Yes this is what I want to do but I think it just makes more since to use BenchClose. The objective was to trade in and out of ETF’s that are uncorrelated. The S&P historically is uncorrelated with Gold and OIL therefore BenchClose works fine.