This is a serious issue. When parents don't pull together and send a clear unified message to the child it will create division on the parental front. What that does is cause confusion in the child's mind and it teaches the child to manipulate the parents. It can develop into resentment, anger and frustration. One parent may think the child’s behaviour is not an issue while the other parent deems it a problem.
There is a solution. Parents need time together to discuss what they want to see in their child. Discuss, talk, converse! Do it until there is agreement on what the expectations are and how you will work to achieve that desire. Agreement is key. Parents should evaluate their child's behaviour. Ask yourself some questions. Do I like what I see and hear in my child? What is it that is bugging me? Why am I so annoyed? Talk questions through with your partner. One of you might be bothered by something and the other doesn't see as a problem. You need to work this out before you will see any change in your child.
For results, both parents need to be in agreement about what they want and how they will go about reaching the desired goal. Then, work at it together, do it consistently and you will see the changes you are looking for.