Some aspects of acceleration of protons and deuterons in single RFQ are considered. If effects of space charge are significantly hath nominal voltage for acceleration of deuterons can be too small to reach high efficiency of bunching and focusing of protons. It is shown that a raising of voltage up to nominal value for deuterons leads to increasing of capture and transmission for protons. Another problem is concerned with a choice of radial matching section parameters, which are optimal for both beams (proton and deuterons) simultaneously. Methods of optimization are discussed. Analysis of particles dynamics is illustrated by calculations results.