It is ok to buy books on Pinduoduo and want to buy more books at the same time. You can choose the books you see or want to buy, click Collection, then enter the personal center and click Collection to view all the goods in your collection. You can choose the books you want to buy together, pay for them together, and buy more books at the same time. If you want a book and want to buy more books at the same time, you can directly select the plus sign next to it to increase the purchase quantity.