how to play double-sliders in the same direction on keyboard

Heya everyone, fellow controller player here! I was just wondering.. How do you play the same directioned double sliders when you play the game with keyboard? I tried playing with my keyboard a couple times, and that is a thing i never really managed to figure out. Any response would be really appreciated! cheers! ^^

triangle + left slider for left double slider
circle + right slider for right double slider