I had first the same problem. Add the second 441 first as ema instead if lwma and add the 620 and so on levels. Finish that and after it you klick on the 441 ema and change it to lwma :-) that does work in my oanda mt4 demo.
pileit1.......my Oanda MT4 kept rejecting a second set of 441 MA lines until I layed down the second set using 440 ma vice 441, Upon laying that 440 MA set down with the 620 levels I immediately changed the 440 MA to 441 MA and it stuck to the chart as hoped for. Hope that helps you.
Oops......DOG replied moments before I did. I expect though that either way will get you around the problem.