In combos with a guitar player, the guitar player usually comps for soloists. If there is both a pianist and a guitarist, as sometimes occurs in organ trios or big bands, they may either alternate comping or comp at the same time. Having two chordal instruments comp at the same time is difficult to do well. The two compers may make different, clashing interpretations of the same chord (e.g., the pianist may add a flat 13th, while the guitarist plays a natural 13th), or the texture may become overly cluttered.