If i already have one open i will not trade the other.
or i may close half of my eurusd and take on half of gbpusd to diversify(but note there are no real diversification in forex as all are correlated somehow).
or if my current open position is profitable enough and breached a key level of interest i will put it to breakeven and enter another at another 2%, effectively still risking 2% while making 8%
Note that when i say close half of eur to buy half of gbp, if eur goes wrong so will your gbp (correlation reason). But you are and should only be risking 2% or even lesser as when you close the half eur you should have some profit in already and hopefully move your stop to a better location if it permits.