is there any way to place a block in different regions without duplicating it . for ex consider a block1 and its display regions requirement
page1 lefttop
page2 right
how to configure block1 in 2 different regions ?
As far as I understand it each block has to be unique, so a block cant be in two places at once using the standard block admin.
Having said that a block is essentially just a function call, so you can get around this limitation programmatically. using something like drupal_set_content(). I really wouldn't take this route though as you will probably run into some unintended and nasty consequences.
However what you probably want is something like Multi Block.