没有明白楼主的意思，能不能说的详细些，最后有数据。结果

假定我的回归式为 Y=x0+bx1+cx2+dx3
如果x2与x3同时具有内生性，
我可以用相同的工具变量来同时instrument x2 x3吗？

不好意思，没讲清楚。

当一个回归式中含有两个或两个以上的内生变量时, then you have an identification issue. In fact, x is an endogenous variable, you have a measure error for x. In this case you need additional equation to define how x is generated or intrumetal variable. Or you need method of instrumental variables. It is not simply “代替”.

Take a look you textbook, to fully understand instrumental variables and it application.