Most competitions are only one entry per person. However on occasions you will find comps that are ‘one entry per household’ or ‘ multiple entries’, read the terms and conditions of a competition for full details. If you cannot find any comment, assume that it is one entry per person.
No, you can enter these as many times as you want to.
You should abide by the terms and conditions of the competition. However as many competition entries are now logged on a computer, it is easier for promoters to check against duplicate entries. It is likely that they will just enter your name once in the competition rather than disqualifying you for accidentally entering twice.
This is a difficult question and worth reading the terms and conditions of each individual case closely to understand.
If there is an entry form, for example, in both Superdrug and Boots unless it says clearly in the terms and conditions that the competition is run by both parties and you can only enter once, they are separate competitions with separate prizes.
You will often find prizes that are seasonal or topical (BBQs in the summer and hampers at Christmas) so it is likely that you will see similar prizes in different competitions, which can be confusing. But unless the t’s and c’s state that a prize is shared between both companies, then treat them as separate comps.
If, after reading the terms and conditions, you are still left unsure, contact The Institute of Promotional Marketing clearly stating your query.