Passport stamps at the border

[BAI]

What is the difference between the following entry stamps given to visitors from non-visa countries. The most common is the usual date stamp with the little endorsement on top: "Leave to enter for 6 months, No work and recourse to PF" and

The date stamp and then another stamp : "Leave to enter is hereby given for/ until" and then 6 MONTHS is written on the dotted line. both of the stamps were given to visitors on arrival but there must be a different meaning to them otherwise the IO could have just stamped the ppt with the first stamp?!

Does anyone know the distinction btwn the two stamps?

[UKBAbble]

The difference is this: The first stamp you describe is the regular stamp for visitors as you say, the second one indicates to other UKBA staff that the landing card will be kept and what was said to the IO is therefore on record.