Perhaps human morality can be seen as both objective and subjective. The objective is perhaps to create social habits which either conform to the subjective will of the majority or to those holding power in order to maintain cohesion or unity within that society. It is changeable, as are the laws used to enforce it.
Arguably that would make the purpose - or, perhaps, benefit - of having morality objective, but the content would remain subjective. The objective benefit would remain a benefit regardless of whether the actual morality were objective or subjective.
For those who believe in the Biblical God, perhaps there is only one moral and the objective is to be in tune with the will of their God which often comes into conflict with human morality.
It's possible that there are objective moral values AND subjective ones, yes - I personally don't see any case standing up for an objective morality given that we have to understand, and our understanding is inherently subjective - we have no objective understanding of anything, and therefore we can have no objective morality. It's arguable that there might be objective morality and we can't be aware of it - i.e. a morality founded in a god - but we have no way to demonstrate that.
I would see the Ten Commandments as an effort to unify the two, where the first 4 are related to the individual and God and the last 6 are related to the individual and society.
Which ten commandments?
The 'ten commandments' are listed differently in three different places in the Bible, and constitute (depending on interpretation) up to twenty-five actual commandments out of hundreds of other pronouncements and behavioural edicts. That said, whether direct instructions constitute 'moral precepts' is another question entirely.
If I follow the ten commandments am I moral because I, say, don't covet my neighbour's ass, am I moral because I follow God's instructions or am I not moral at all because I'm not making moral judgements, I'm just blindly following instructions?
O.