Regarding the weight variable used for analyzing the child weight, it is depending on the background. If you take only the children living with an interviewed mother, it is better to use the variable V005, the child's mother's weight. If you take all children measured in the household, it is better to use the household weight HV005. Regarding the repeated values of the weight variable (either HV005 or V005), note that the weight is a cluster level weight in DHS surveys, all HH in the same cluster share the same weight; all women in the same cluster share the same weight. So this is not a concern.
Thanks
Ruilin