It happens, not very uncommon. If the agent is working both side you may be able to get them to drop the commissions a bit. But you do need to be watchful for any sign they don't have your best interests in mind. Although, that issue is the same in every transaction. Some agents only want to close deals, regardless of what's best for the customer. Some are great. Like anything else, trust but verify. RE agents make a lot of money, in return you should expect a high level of service, ethics and integrity. If you aren't getting those you have the wrong agent. If you don't need those, you shouldn't use an agent.
Stupid people focus on the math, smart people focus on the information.