TIP: Add more than one of the same layer style

If you want to add more than one of the same layer style to one layer, you can't, unless....
you turn the layer into a Smart Object. Start by adding a stroke Layer Style to your layer, then convert it to a Smart Object. Then add a different stroke Layer Style (different color, position and/or size) to the Smart Object. If you want to adjust the first stroke, double-click on the Smart Object to edit it.
You'll ll have to play a bit to get the results you want, but check it out, it's pretty cool.