In Baan ERP with every session we have 2 menu items called
Calculator and calendar.But to my surprise both are having a short cut with F2 key. Is it a mistake?

No, Jack, it's context related.
If you are inside an input field which expects a date, F2 will popup the calendar. Otherwise, the calculator appears.

Not sure about the context in our version, we have a case with BaaN support for this issue.

SITUATION DESCRIPTION:
The form options "Calendar" and "Calculator" have the same shortcut "F2". The customer prefers it to be different one for each.

SOLUTION DESCRIPTION:
Logged a defect # 208384 with "Enhancement Request" priority.