Both Merger and Separation  of public sector units are done by government for destabilisation of these PSUS. Timing may be different, but intention is the same.
The merger of Air India and Indian Airlines, BSNL and MTNL, SBI and affiliated Banks are part of this game as also the separation of BSNL, MTNL, and VSNL.
The government should remember that PSUs are created for the service to the nation and are not play toys to be used for the interest of Corporates and big business.