  In the present paper we show that within all the uncertainties that govern
the process of Roche lobe overflow in Case Br type massive binaries, it can not
be excluded that a significant fraction of them merge and become single stars.
We demonstrate that at least some of them will spend most of their core helium
burning phase as hydrogen rich blue stars, populating the massive blue
supergiant region and/or the massive Be type star population. The evolutionary
simulations let us suspect that these mergers will explode as luminous hydrogen
rich stars and it is tempting to link them to at least some super luminous
supernovae.
