Both of them (Losartan and candersartan) belong to the same class of drugs-Angiotensin receptor blockers. Combination drugs are given in hypertension to impact on many pathways in the pathogenesis of hypertension using a fairly low dose with almost negligible side effect profile and this has been proven useful in many other conditions. There is no scientific evidence to give double of the same class of drugs because both of them have some similar class effect but with little pharmacokinetic properties that may be considered superior based on compelling indication prescriptions pattern.
Two antihypertensives of the same class are not combined. If the blood pressure is not balanced, other classes can be associated, such as thiazide diuretics, calcium channel blockers, etc.