Does Lobachevsky's V axiom deny Euclid's V axiom

Well, they're practically  negation of each other.
And you won't find a rule "not p is not necessarily
denying p" in mathematics - but it is an usual component
of pseudophilosophies concocted by morons for excusing
both their inconsistencies and plain lies.
So - the question is as in the topic. What do you think?