Is it ok to send a value to the lvalue argument using std::move?

I have a function of the form void foo(std::string str);

I want to use it in two scenarios:

1. send a copy of the original value to it:

   std::string myString = "any data that I want to keep in its original state"
   foo(myString);
   

2. pass it the original value using std::move:

   std::string myString = "any data that I don't need anymore"
   foo(std::move(myString));
   

Is it ok to send a value to the lvalue argument using std::move?

Yes it's OK here.

foo is accepting its parameter by value, so it has to be constructed somehow.

In your 1st case, the str parameter is copy-constructed from the passed argument.

In your 2nd case (with the std::move), the str parameter is move-constructed from the passed argument (this will leave the moved-from myString in a valid but unspecified state).

A side note:
Using a by value parameter to support both copy and move is quite a common idiom.
One example is implementing an assignment operator with a by value parameter together with the copy-and-swap idiom.
See some more info here: What is the copy-and-swap idiom?.