Du Shenquan was military governor of Hezhong twice — once briefly in 859 and once starting in 870, and it was unclear how long the 870 commission lasted; still, that put a timeframe on Pei's service under Du. See Old Book of Tang, vol. 177.
Wang Duo was removed from and restored to chancellorship multiple times, and this event could be referring to Wang's removal in 873 or 879 — although, since Wang's removal in 873 was nominally not a removal (as, while he was sent out to Xuanwu Circuit to serve as its military governor, he retained the chancellor title as an honorary title), it appeared that the reference was likely to the 879 removal. See Zizhi Tongjian, vols. 252, 253.
