Clonazepam (Klonopin) and lorazepam (Ativan) are both benzos with similar effects. You can combine amphetamines and benzos, but the sedating effects of the benzos will be partially counter-acted by the stimulant effects of the amphetamines (Adderall).
Because clonazepam and lorazepam are both benzos, there will be some cross-tolerance from you taking the lorazepam earlier.
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