The last sentence of rule 2.0B1 allows the cataloger to treat as a single chief source successive leaves or pages.  The intent of this provision is not to combine separate title pages, however.  Separate title pages usually repeat everything.  The intent is for a spread of single title page data.  It is true that in such a spread some elements may be repeated (as the provision recognizes).  A tip-off that this provision is applicable is either no repetition or a partial repetition.  Conversely, complete repetition is a tip-off of non-applicability.

See also:

2.0.  General Rules