How could the goverment grant this patent number w0199603864a1,when Rodney M McGee Sr. invented this in patent number 4858456 in 1988.
The easy answer to the question is No patent has been granted.
The document you are referring to, W0199603864a1 is not a granted patent. It is not even a U.S. national patent application at this point. Documents starting with WO are international PCT (Patent Cooperation Treaty) applications. I have not compared the substance of the two documents but any new application should not ultimately issue as a patent unless its claims define something new and non-obvious.
Sometimes a claim is written so specifically and narrowly that while it is different than what was was done in the past, but nobody cares. A very narrow claim can generally be gotten around easily. The claim 1 in W0199603864a1 is one of the longest claims I have seen and may be in that category.