Question: solution of liner program, unique?

I tryto solve a linear program of big dimension using LPSolve function. My problem is that is returns a solution but I am not sure if it is unique or not, and for me it is really important.

I saw that in the new version there are options for LPSolve: method=interiorpoint or activeset. If I understood correctly, interiorpoint gives a solution in the middle of the interval and the activepoint - in the corner. My idea was to run LPSolve twice using those two methods. If the result is the same then the solution is unique.

My problem is that LPSolve with the option interior point does not work for my problem. I get an error message. However, it works fine with the option activeset.

Could you please tell me, probably there is another way to check if the solution is unique or not?

Thank you in advance.