I have been trying to understand, if there is any difference between Choice of Law and Governing Law clauses, mentioned in contracts? If no, what is the difference and can they both be in the same contract?
Usually, "Choice of Law" and "Governing Law" mean the same thing and there would usually be only one or the other. I've never seen a contract with both in twenty years as a lawyer, but all sorts of weird stuff gets written into contracts especially by amateurs. A term like this is often important because it can often be unclear which state's law applies to a contract otherwise.
Not infrequently, there would be both a "Choice of Law" paragraph stating which law applies to the contract in which circumstances, and a separate "Choice of Forum" provision (somethings given a different title such as "Dispute Resolution" or "Forum" or "Venue") which states which court the contract can be enforced in, since a forum court can often apply the law of another state as to some issues in a case.
For example, usually, consumer contracts can only be enforced in a court for a jurisdiction in which the defendant consumer resides, even though the contract might provide that the governing law is the law of the place where the company suing the consumer is based.
I often write (business to business) contracts that provide that Colorado law shall apply and that any suit to enforce the contract shall be brought in the state courts of the state of Colorado in the county where the business writing the court is located and that the parties waive any right to a trial by jury.