Do not confuse validity with stay
A visa or permit can have an overall use period and a separate permitted stay after entry. Read the grant conditions rather than assuming the two dates are identical.
Easy Visitor Permit stay periods
Current ICA class information defines the 30-day and 60-day Easy Visitor Permit routes by the permitted stay from arrival and identifies them as single-entry.
Multiple-entry classes work differently
For example, the current Business Short-Term Multiple Entry class is described as valid for 12 months with up to 60 days from each arrival. That structure should not be copied onto visitor permits.
Use the grant document as the final reference
The conditions on the visa decision or authority to travel govern the individual permission. Check those details before departure.