Sometimes it happens that the phase name and some settings (not all) are copied unintentionally from one phase to the other.
One way this can happen is when dragging the mouse (while holding down the left mouse button) from a phase A onto the calculation marker / icon (that is in front of the phase name in the phase list) of another phase B. Then it can also copy settings as time interval, reset displacements to zero, ignore undrained behaviour etc. from phase A to phase B.
This can simply happen when one for instance very swiftly selects phase A, then phase B, then phase C. By clicking to select and moving the mouse one could in fact drag phase A a tiny bit over phase B directly below and then when selecting phase B copy the phase name and (some) phase settings.
Users are advised to carefully inspect the phases and their settings prior to calculation and adjust if relevant.
This issue is improved since PLAXIS 2D2012.01