The sale period of item A and the sale period of item B overlap for a short time.
There's a slight overlap in the end of the sale period of item A and the beginning of the sale period of item B.
ーThe sale period of item A and the sale period of item B overlap for a short time.
「商品Aの販売期間と商品Bの販売期間は短期間重複している」
sale period で「販売期間」
to overlap で「重複する・かち合う」
ーThere's a slight overlap in the end of the sale period of item A and the beginning of the sale period of item B.
「商品Aの販売期間の最後と商品Bの販売期間の頭には少し重複がある」
There's a slight overlap ... で「少しの部分的重複がある」と言えます。
ご参考まで!
The sales periods for Product A and Product B overlap.
The sales periods for Product A and Product B overlap.
There is an overlap in the sales periods of Product A and Product B.
ビジネスや仕事の場面で「期間が重複している」「被っている」と言いたい場合、英語では overlap(オーバーラップ)という動詞や名詞を使うのが自然で一般的です。