How to play double stops. Well, you basically play two notes at a time, and whatever combination that is, is entirely up to you. You can keep them close together, or further apart, then combinations thereof. So, really, it's just a matter of using your two fingers together or a thumb and a finger. Generally speaking, when you're going to be playing you're going to be using your thumb and your second finger at the most.
The first finger is going to drop in occasionally, as needed. But when you're doing a lot of picking stuff, if you've got a choice between the two, go for the second one. You've got a little bit more space to work with. You're going to be less likely to get jammed up because of the proximity of the first finger and the thumb. But, I mean, with a ten-string instrument you have limitless possibilities for double stops, or really pretty much any kind of stops.
So those are just some examples of what you can do. Again, you can engage a pedal leading into it as with E lower to kick things off. It's always good with pedal steel to give the impression that you're coming from somewhere and going somewhere, too. You don't want to be just... This is kind of static. It's a lot less interesting than... which is reaching the same result but something happened. You went from point A to point B, and that applies to anything you're going to do.
That's the kind of thing you want to be hearing. You don't want to sound like you're just dragging from one place to the next in sort of a rigid way. So, that's it for double stops.