Potentially yes but it's all fact dependent and what position is approaching death and the erelationships with the children.
Relaations with the children - it doesn't follow that all children are 'equal' in the eyes of the parents or will have good/loving relationships. I don't think Lizzie Borden's parents would be rushing to give her a chunky inheritance if they had survived. JOking but you take the point. It does happen that some children are absolutely abusive to their parents - and that can happen whether they have children or are childless.
Age of the grandchild and relations with grandchildren - if the grandchildren are adults, grandparent may by that point have independent relationships with them and better relttions with some rather than others and want to give one or more different sums. They may 'factor' that in to what they leave to their own children vs grandchildren. If grandchildren are v. young, more likely to leave money to parents for them to sort out.
Amount of money involved, wealth of relative parties - if parent has an average amount and one of the children is Bill Gates, may as well leave it all to the poverty stricken other child. If very wealthy, may be tax advantages in leaving the share to their child who has children all to the grandchildren (taxed once rather than taxed twice on death of their own child).
Care - childless adult child is far more likely to be heavily involved in care - sometimes giving up income and job and whole life to care for infirm parents. They will take a heavy financial hit without expectation if they aren't working or working reduced hours usually so it's not uncommon for a parent in that situation to address that 'loss' they have 'caused' (inverted commas as it's not their fault) to the carer sibling in inheritance - sort of to 'do right' by the one that has looked after them.
Single adult child (no family of their own) is potentially (subject to their own income/financial status) in old age/future than the one with children/family who will have an extended family most likely to offer help and support. Parent may want to leave a bit more to the single one to give them a bit more old age secuirty.
Lots of variables so I'd say it depends but there could be lots of reasons why it is fairer to not divide 50/50.