The Asterisk internal library that reads configuration files allows you to restart a section by suffixing it with “(+)”. What the OP is saying is that PJSIP allows one to use the same section name for more than one purpose, in the same file.
Either the PJSIP configuration code is not using the standard Asterisk parsing code, or it allows a section to contain more than one type of item, relying on different keywords to unscramble them.
Both would be confusing if you use templates (so the template suggestion was not a good one) or try and continue a section.