In uk.rec.gardening R H Draney wrote:
I've come across that several times in my family tree. I think one poor
family had three attempts to get a child called John, before
succeeding. It seems - in these cases - either an attempt to carry on
a family name, or perhaps a tribute to the child that had died. In our
own time, a friend of mine considered calling a new son after a
cot-death baby. She didn't.

I've heard that some bereaved parents did this as a folk protection against the
Grim Reaper taking away the new child; the idea was to confuse the spirits into
thinking that they had already taken this one....r

I can imagine it being rather confusing for /everyone/, unless they
dismissed any reference to the first child from any future conversation!