Edit:
According to 現代漢語八百詞 (p.630), 有 (which means “possess”) is a verb that can follow a monosyllabic verb to form a tightly-bound term. In linguistic terms, it is called a serial verb compound.
桌上有一卷书 (there is a book on the table)
桌上摆有一卷书 (there is a book placed on the table) - 摆 explains how the book is situated on the table -- it laid/ sits there
More example:
庭中有几棵树 (There are several trees in the courtyard)
庭中种有几棵树 (There are several trees planted in the courtyard) - 種 explains how the trees are situated in the courtyard -- they grow there
車上有四人 (There are four people in the car)
車上坐有四人 (There are four people sitting in the car)
屋中有一百袋大米 (There are a hundred bags of rice in the house)
屋中堆有一百袋大米 (There are a hundred bags of rice piled up in the house)
手中有一把七尺長刀 (Have a seven-foot-long knife in hand)
手中持有一把七尺長刀 (Have a seven-foot-long knife holding in hand)
Different verbs can work with 有 in the above sentences. e.g. 庭中横放有几棵树, 车上躺有四人, 屋中藏有一百袋大米; 手中握有一把七尺长刀