The New Netherland Project naming convention says that for a child whose baptism record shows the father recorded with a modern-style surname, such as Terhuijne or Ter Heun or Terhune or Terhuyne, the last name of the father on the baptism record is the name we use for the LNAB of the child. This can mean that children in one family often have different LNABs (spellings varied wildly in New Netherland), but to aid in searching for the person we record all of their known names in the profile data section.
See Project:New Netherland Settlers #Naming Conventions for more details (more details than you probably want to know).
For now, it is best to just focus on using the best LNAB for the new profiles you are creating. The names on existing profiles (including Albert and his son Stephanus/Stephen) can be corrected later, if needed. (Because WikiTree uses the LNAB as an ID, it is best to minimize LNAB changes. Accordingly, we are exhorted to determine a good LNAB before creating a new profile and it is important to do this before merging multiple profiles, but it is not so urgent to change LNAB on an existing profile that does not need merging.)
I am not surprised that you have not found Albert recorded with the patronymic name of Jansen; it looks like it may have been inserted by genealogists as a convenience to reduce confusion. However, it is possible that it is in land records, court records, or other documents. You might want to add a profile message or a research note indicating that you have not found any records that give him a patronymic name. (Note: Our Dutch cousins here in WikiTree tell us that patronymic names of Dutch people should never ever be called middle names...)
