Residential sale agreement

I am planning to sell a residential plot that I own. One of the brokers is interested in purchasing the plot.

He sent me 2 different sale agreements with 2 different amounts. When asked, he said one of the sale agreement (that has slightly lower sale price) is for getting a bank loan. But he said he will pay me the higher amount that's on the other sale agreement.

Is this common? What if he pays the lower amount at the time of registration? Can I refuse to register the plot in his name?