Hova is right, oanda opens earlier than alpari so you need to match the times up. If you count the bars back from the last bar on each chart you will see they match almost perfectly but it seems that alpari is missing data, but it was just that it wasn't open for trading yet so no price action. This is why people say that weekend gaps in the forex are not real gaps because it depends on what time your broker opens, so the gaps will be different from broker to broker and oanda never shows a gap because it is the first to open
I believe it's because of opening hours. Oanda is based in Canada while Alpari UK is based in UK. (fyi if u try Alpari NZ, and compare to Alpari UK, the graph looks different too)
By the way, Oanda is a MM while Apari UK is not. So maybe they were stop-hunting? I tend not to trust any MM brokers, but then again if i had to choose a MM to trade with i will use Oanda.