Short answer. No — double. Article 1006 provides that where brothers and sisters of the full blood survive together with brothers and sisters of the half blood, the former are entitled to a share double that of the latter. Your full brother takes two units for every one your half brother takes.
What the law says
Should brother and sisters of the full blood survive together with brothers and sisters of the half blood, the former shall be entitled to a share double that of the latter.
Civil Code, Article 1006 — Full Blood Takes Double the Half Blood. Read the full provision →
A two-to-one ratio, not a fixed fraction
The rule states a relationship rather than a number: the full-blood siblings are entitled to a share double that of the latter. It is proportional, so it produces different fractions depending on how many siblings there are on each side, and it operates only where both kinds survive together. Where every surviving sibling is of the full blood, or every one of them is of the half blood, they simply share equally and this article never comes into play. It is the mixed case that the provision was written for.
What full blood and half blood mean here
Full blood means both parents in common with the deceased; half blood means one. So a brother who shares your father but not your mother is of the half blood as against a sibling who shares both, and the label has nothing to do with who grew up in which household or how close the relationship was. The comparison is always with the deceased, not with each other — a person can be your full brother and the deceased's half brother, which is why the family tree has to be drawn from the deceased outward rather than from whoever is asking.
Working the shares out
Count in units: two for each full-blood sibling, one for each of the half blood, then divide the estate by the total. One full brother and one half brother give three units, so the full brother takes two-thirds and the half brother one-third. Two full and two half give six units — a third to each full-blood sibling and a sixth to each of the others. Nephews and nieces representing a sibling who died before the deceased take that sibling's unit value, so a branch does not gain or lose by how many people are standing in it.
Siblings only inherit at a certain point
Before applying the ratio, confirm that brothers and sisters inherit in this estate at all. They are reached only where the deceased left no descendants and no ascendants, so a surviving child or parent displaces them completely. A surviving spouse does not displace them but does share with them, taking half the estate and leaving the siblings to divide the other half — and it is inside that half that the two-to-one ratio then operates. Establish the full list of survivors and the parentage of each sibling from civil registry records before proposing any figures.