On the same currency pair?
If you trade in the US, you can’t, government prohibits long/short on the same pair.
Also they implemented FIFO rule (First In First Out).
If you really want to trade the same pair both ways, you need a “workaround”.
You have to open a “sub-account” with Oanda then you can go either way again.
Man, you are even better then Oanda’s Helpdesk. Thanks! 
I’m trading from Portugal so that wouldn’t be a problem. Just for curiosity, do you know why the US government prohibits simultaneous long and short orders?
Yes the official version is as follows:
(Rule 2-43) NFA (National Futures Association) believes that “hedging” serves no economic purpose for the account holder and actually benefits the FDM (Forex Dealer Member) because of the interest costs the customer will ultimately pay to the FDM and because the FDM, in essence, receives double fees (the pip spread) on a “hedging” transaction.
Unofficially I think the brokers are realizing that you got a slight edge with going both ways (hedging) because as soon as you would see a trend you cancel the loosing one, especially on low spread brokers.
They just did not want to be the “bad guys” so they got the government involved to make this rules for them. That’s my take on it.
Portugal, no problem to trade both ways.
Hedged in my early trading strategy testing phase a view years back, with mixed results. Maybe I was just a “Forex Greenhorn” and that’s why the results did not match my expectation
As a strategy it’s a perfectly well KIS(S) strategy, and
Simplicity is the key for profit. Period!!!