Article usage in compound predicate nouns
Solution 1:
Neither is incorrect, but the latter would be preferred for clarity, since the omission is not efficient enough to justify the change. The former is a grammatically valid ellipsis of the second article, i.e. the second article is understood rather than written/spoken. According to a quick and dirty Ngram, the two options are close in popularity, with a slight leaning toward retaining both articles.