It's one or the other - stapled shares, or, CDIs. If you didn't elect the shares, then you would by default have the CDIs.
There's more to it than what I'll say, but the basic premise in this instance is the CDIs are listed locally, while the stapled shares are the underlying stock trading abroad. The CDIs for you will actually be rounded down from 369 to 360, with the 9 fractional 'leftovers' sold and paid to you.
The OMN shares are additional - for you, 1000/20 = 50