。
She has twice as many CDs as I do.
Literal
She [topic-は] my 2-times [possessive-の] CDs [object-を] has.
The ~倍 multiplier construction works on any countable item — here, CDs. CD is a Latin-letter abbreviation that has been fully naturalized in Japanese, written as ＣＤ (full-width Latin) here — a typographic choice common in Japanese text where mixed Japanese and Latin scripts are present. Note the polite ending 持っています rather than plain 持っている, raising the register slightly toward polite conversation.