  Recent observation of unusual vortex patterns in MgB_2 single crystals raised
speculations about a new type of superconductivity (named "type-1.5"). However,
the strict application of the standard two-band Ginzburg-Landau (GL) theory
results in simply proportional order parameters of the two bands - and does not
support the "type-1.5" behavior. Here we derive the extended GL formalism
(accounting all terms of the next order over the small t= 1- T/T_c parameter)
for a two-band clean s-wave superconductor and show that the two condensates
generally have different spatial scales, with difference disappearing only in
the limit T -> T_c. The extended version of the two-band GL formalism improves
the validity of GL theory below T_c, and suggests revisiting of the earlier
calculations based on the standard model.
