Have you followed up the citations given in VCH Essex vol. 7 p. 118?
(here:
https://www.british-history.ac.uk/vch/essex/vol7/pp117-126):
"By 1187 William Doo (D'Ou) possessed the manor. The witnessing clauses
of certain grants to Brook Street hospital, South Weald, in 1163 × 1187
and 1275, with other evidence, suggest that in the 12th century there
existed a family, holding the manors of South Ockendon and Willingdale
Doe (Essex) and (Market) Lavington (Wilts.), for whom the names of Ou
and Rochelle were interchangeable. (fn. 33: Reg. Sudbury (Cant. & York
Soc.), i. 210–11; Cart. Mon. Sancti Johannis Baptiste de Colecestria
(Roxburghe Club) i. 4; E.A.T. N.S. viii. 375; Feet of F. Essex, i.
272–3; Reg. Regum Anglo-Norm. iii, p. 102; Cur. Reg. R. x. 108; E.R.O.,
T/P 195/2, p. 6; V.C.H. Wilts, x. 87.) Godfrey de la Rochelle, who lived
under Henry I, was apparently succeeded by his daughter Agnes, she by
her son Richard de la Rochelle, who died before 1195, and he by his son
William de la Rochelle. (fn. 34: Cur. Reg. R. x. 108. William was
already paying scutage for the Lavington manor in 1194–5: Red Bk. Exch.
(Rolls Ser.), i. 89.) William had died by 1198. (fn. 35: Pipe R. 1198
(P.R.S. N.S. ix), 138.) His heir, also named William de la Rochelle,
succeeded as a minor and died c. 1226. (fn. 36: Cur. Reg. R. xi. 469;
Bk. of Fees, ii. 1347, 1349.) (Sir) Richard de la Rochelle, heir of the
last-named William, was still a minor in 1234, but was married a decade
later, and by 1255 had entered on an Irish career, first as deputy to
the Justiciar of Ireland, and from 1261 as Justiciar himself. (fn. 37:
Close R. 1231–4, 373; 1242–7, 207; 1254–6, 158–9; 1261–4, 11.)"
If William (died ca 1226) was a minor when he succeeded by 1198 and his
heir Richard was still a minor in 1234 it is apparent that these two
belonged to different, and probably successive, generations. Collateral
inheritance does not usually work out that way, as inheritance by a
cousin is more common than by a cousin once (or more than once) removed.