How to avoid multiple Inclusions of perl modules.. or how to detect mutliple inclusions.

i have many modules which inturn use among themselvs.. some times i
get the following error..
Can't locate <>.pm in @INC though it is present in that location.. i
doubt this occurs because of multiple or cyclic inclusions of
modules..
can any one suggest the way to find the error or avoidin them ?
thanks in advance
.