你可能觉得两个"有"使得句子结构显得很怪异, 你可能会问: "到底哪个'有'是谓语动词? "但是, 对于"有"这个词来说, 是允许这样的. 而且第二个动词可以不是"有". e,g, 中国有65%的家庭是三口之家. (The 2nd verb is "是") BTW: 第一个"有"其实可以省略. Actually the 1st "有" in each sentence above is optional. I think you are more familiar with the case without it.

句子是对的，第一个有可以省略

It's very normal to have "double subjects" in a Chinese sentence. 中国有(65%的家庭有啃老现象). If you do not want to use "有", you can write in this way...中国有(65%的家庭存在啃老现象)。

There are 65% families that have the boomerang kid phenomenon in China. "are" and "have". “有啃老现象” 作宾语补足语 object clause

用英语思维去理解，“中国有”=“There be...in China","65%的家庭有啃老现象"="Up to 65% of the families(in China)have the phenomenon of the older raising their children."