proved, proven
The two forms relate to two different verbs derived from Old French prover (ultimately from Latin probare). In standard BrE, proved is the normal past tense and past participle of the verb prove (They proved their point / Their point was proved). Proven survived as a past participle in dialect use and is current in the Scottish legal term not proven (usually pronounced proh-vǝn) and occasionally in general use in Britain generally (pronounced proo-vǝn), especially in attributive position (i.e. before a noun):

• His love of precise dates and proven facts —N. Shakespeare, 1989.

In AmE, proven is at least as common as proved both as a past tense and as a past participle.

Modern English usage. 2014.