I have found this situation too when a person's birth appears to have been registered more than once, the second one some years later and added at the bottom of the page and handwritten, though I haven't come across one that was registered three times before! They do all relate to the same person.
This happens when some alteration or correction to the birth details is necessary.
As a Birth Certificate is an official document, it cannot be altered once issued. Therefore if it needs to be amended it is necessary to issue a new Certificate which is then inserted in the index at the date when it was issued. The birth indexes do not indicate when someone was born so much as when the birth was registered, which should by law be within six weeks of the birth but, if it is not done at the proper time, the birth will be indexed at the date when it was registered.
In a case I found, a daughter was born to a couple who were not married (the father was married to someone else) and the birth was registered accordingly. Some years later, the father's wife died and he was able to marry the mother. The daughter was now legitimized and a new Birth Certificate issued to reflect that. The second entry in the index appeared in the quarter when the new details were registered. There was also a handwritten note on the page containing the first entry that referred to the quarter and year of the later registration.
Of course, there could be many other reasons why an amended Birth Certificate would need to be issued at a later date.