A muḥkam report is an accepted narration with no other accepted narration apparently contradicting it. Its meaning still requires attention to context, generality, specification and related evidence.
Mukhtalif al-ḥadīth concerns two accepted narrations whose outward meanings seem incompatible. Acceptance of both is the starting requirement. Opposition from an unreliable route does not by itself turn the sound report into a genuine case of conflicting accepted evidence.
For instance, one authentic general statement and another authentic particular statement about the same ruling may be reconciled by treating the particular as an explanation or qualification of the general rather than a contradiction.