An objection attributed to Ibn Hibban concerns the apparent absence of a narration restricted to precisely two narrators transmitting from precisely two throughout. The issue becomes clearer once the definition is interpreted carefully.
An exactly two-by-two structure throughout would allow no later expansion at all; the absence of that extremely narrow pattern is one claim.
The technical aziz pattern requires that transmission never drop below two at a relevant stage, while permitting the number of later narrators to increase; this is a real and intelligible possibility.
These are not equivalent definitions. Many terminological disagreements arise from assuming that an illustrative number must be fixed at every later point instead of identifying the minimum required by the category.