This is a difficult question because homonymous siblings are frequent up to the 20th century. And inadvertent merges of siblings do occur. I personnally dislike adding something to the name fields (like, "First", "Second", "died Young".. whatever).
So, I try to state it clearly at the BEGINNING of the bio: "Not to be confused with xxxx, his brother, who was born (give birth date, hopefully different from the one who is profiled). I even wondered if it would be interesting to develop a "Homonymous siblings" pattern box.
Please be aware that sometimes two siblings with the same name get to adult age. It is not always the recycling of the name of a child who died in infancy. At least in my culture (French, RC) it was not uncommon to have a much elder sibling (say 10 years older) be the godparent of the younger one, with the same first name. Families dealt with that by using nicknames, so that their official baptism name was rarely used. Unfortunately, we have no records of what the call names were.
The next thing to do - after fleshing up the bio to make it clear there are different profiles with the same names - is to set up a Rejected Match. This would at least delay a bad merge, though it's not completely foolproof.
And last - why are death dates not visible in search results? If they are not, it would definitely be a good improvement to add them.