Can anyone help? Why does my birth appear in two different years in the index of births?

[Alsowondering]

Can anyone help me with this please?

My birth appears twice on the register of births three years apart (I'm using FreeBMD).

I know my parents weren't married when I was born, but they married within six months of my birth. They are definitely both my biological parents.

My birth appears in the records for the correct quarter I was born with a reference written in pen next to it.

The reference refers to a further entry for my birth three years later (which happens to be a few months after my sibling was born). Very uncommon name and the reference written on the earlier register directly refers to the entry three years later and mother's maiden name etc matches.

I'm baffled. I wonder if it's something similar to do with my parents being unmarried? I've never actually seen my birth certificate and wonder if this is why (DM has it for safekeeping which is fine!)

The most likely is that your birth was re-registered after the marriage to make you a legal child of the marriage.

Previously that had an impact on parental rights for fathers and inheritance rights for children.

it’s possible your parents only found that out after having your sibling.

Also I should say that FreeBMD does flag the entry in the quarter I was born as a late entry - but I don't really understand why and what it means.

It might have something to do with re registering a birth after marriage. When we had a civil partnership we where told to re register our son who was born 2 year before. We actually still haven't done it.

If your parents were unmarried at the time of your birth they would probably have re-registered you after their marriage. They were perhaps reminded by the Registrar to do it when they went to register your sister. If you were born after 1969 and have a full birth certificate it will say 'on the authority of the Registrar General in the date box near the bottom.

If your parents marry after your birth is registered, your birth should really be re registered with the updated details. So maybe when registering your sibling the registrar has suggested doing yours again.

I only discovered in my 20's that my birth should have been re registered but it never was.

Why don't you order copies of both certificates?

Ring the registry office for your area, and ask.