Hi
I see what you mean in 1915. Same name volume and page numbers. Very strange.
If you go to birth image pages for 1898 June quarter and go to the letter S and scroll through the pages until you get to the Soanes. - you will see that Peter Henry R Soane was registered Hackney. 1898. 1B. page 533. As I mentioned it is on Free BMD for 1898. When you go to the 1915 there is no image to see. So seems a bit odd.
Hope this helps and that if you order the certificate for the 1898 entry it is some help. It would say where the family were and maybe some more info.
Regards
Norma