No, what you do is fingerpick the 3 or the open one, while you hit the other one with the pick. Or even play the song with fingers all thru. You are supposed to hit them at the same time, and not to mute. If they wanted you to mute them, the string would be "X". Cheers.
Finger pick it, rather than using an ordinary pick. So play the D open with your thumb and the B on the third fret with another finger, index or middle. Or you can still hold the pick and play the D with the pick and the B with another finger, your choice.
Alright, finger picking it is.
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