It is possible to arrange multiple references within the same brackets by doing \cite{paper1,paper2} instead of \cite{paper1}\cite{paper2}. The former will produce for example [1,2] and the latter will produce [1][2]. The former approach is considered better.
However, sometimes the ordering among the citations within a multiple citation might not come right. For example, \cite{paper1,paper2} might produce [2,1] instead of [1,2]. Here again, it is considered better to order citations in a multiple citation according to the order they appear in the references list. To make sure they are ordered as such add \usepackage{cite} in the preamble of your latex source file.
However, sometimes the ordering among the citations within a multiple citation might not come right. For example, \cite{paper1,paper2} might produce [2,1] instead of [1,2]. Here again, it is considered better to order citations in a multiple citation according to the order they appear in the references list. To make sure they are ordered as such add \usepackage{cite} in the preamble of your latex source file.
