Is this a standard tactic?

I bought eur/gbp at 88.40 before the london open and uk gdp release at 0930.

The trade went in profit about 12 pips and I should have got SL to BE as it was an important data release. (I didnt and my SL got hit)

Would it have been a good idea to also sell around 88.50 with sl around 20 pips. That way I win either way after the data release and its sort of a hedge?

Not sure what you mean. You're long, so if you sell at 88.50, you've made 10 pips profit and are flat. If for some reason you want to hold two open positions one long and the other short, with stops of 20, then there is no guarantee the news won't make it spike up take out the short position's stop, then reverse quickly and take out the long positions stop and you lose twice your risk, plus the 10 pips profit you could have had. Also the stops are not guaranteed to execute at the right price in news.

This relies on getting in before the news and hoping for a spike. I could have gotten the buy to BE and then had a sell at 88.50 with say 20 pip SL risking 0.5% of account. If there is a spike, one of the stops gets taken out, but I still make profit, no spike, I can close trade or keep them both making pretty much no loss if market doesnt move much. I haven't done any calculations, was just an idea.

So for my eur/gbp trade before gdp this morning: Put SL from the buy at 88.40 when market was at 88.53 and then sell at market rising 0.5% with 20 pip SL. GDP came in much better than expected. Price sunk, would have taken out my SL at BE and my sell would be in profit.

If gdp came out as expected or worse, I can close the sell...

You already have a profit. You bought at 88.40 and price is at 88.53, you have a running profit.

Now you are suggesting having an order to sell (but not close your long??). Well suppose your platform allows that, and doesn't make you flat. Isn't there a chance price spikes down, stops out long at 88.40, then reverses sharply and shoots above where your short position was. Now in that case, you had a profit of 13 pips initially, which you then gave up for breakeven (or worse if your stop filled lower), and you have a short position which is showing a loss.

There is no cheat to get around this. If it goes strongly in one direction, then yeah you could profit. If it just spikes up and down and returns to where it was, or spikes one way stopping you out and then goes the other direction strongly, you're screwed.

Take your profit, and decide whether you really want to be long or short before that news.