I don't know whether this situation was applicable at the time or not, but here is an example of a player either A) signing for less guaranteed money than other offers, or B) a CPU team offering higher than the limit.
CB Daniel Coats, Cust-10, 2017 FA 2 (currently page 58), signed with Manhattan for $83,804,162/6 years. The max (with 75% guaranteed) should have been $82,032,330/6 years, which was offered by three other teams.