What is the test for determining whether there is double jeopardy?

" ' "The constitutional prohibition against 'double jeopardy' was designed to protect an individual from being subjected to the hazards of trial and possible conviction more than once for an alleged offense. . . ." ' [Citation.] Courts 'have disparaged "rigid, mechanical" rules in the interpretation of the Double Jeopardy Clause. [Citation.]' [Citation.] 'The exaltation of form over substance is to be avoided.' [Citation.] The standards for determining when a double jeopardy violation has occurred are not to be applied mechanically." (People v. Saunders, supra, 5 Cal.4th at p. 593)