hmm wrote an answer but it disapeard .
ok I will answer again
I think maybe your problem is in two places , try to rewrite these places with code below
maybe this helps...

if (v1.active == true && v2.active == true)
							{
									v1pos -= cv * ((1 - t) * lambda / 2.0f) * fraction;   //   (1-t)/2
									v2pos -= cv * (t * lambda / 2.0f) * fraction;	 	 //	 t/2		   ( t+(1-t))/2=1/2   half energy for edge
							}
							else if (v1.active == false && v2.active == true)
							{
									v2pos -= cv * (t * lambda/2.0f) * fraction;   	 	 //half energy for edge
							}
							else if (v1.active == true && v2.active == false)
							{
									v1pos -= cv * ((1 - t) * lambda/2.0f) * fraction;	 //half energy
							}
mpos += cv * fraction/2.0f;				   // if half energy for edge so must leav half energy to m 	  

About mass, ofcouse if mass different , collision will effect diferently for that objects

//redistribute energy to objects with different mass
float c=1/(obj1.invmass+obj2.invmass);
obj1.vec -= obj1.invmass*c/2*collision_vector;
obj2.vec += obj1.invmass*c/2*collision_vector;
//invmas=1/mass;

hmm wrote an answer but it disapeard .
ok I will answer again
I think maybe your problem is in two places , try to rewrite these places with code below
maybe this helps...

if (v1.active == true && v2.active == true)
							{
									v1pos -= cv * ((1 - t) * lambda / 2.0f) * fraction;   //   (1-t)/2
									v2pos -= cv * (t * lambda / 2.0f) * fraction;	 	 //	 t/2		   ( t+(1-t))/2=1/2   half energy for edge
							}
							else if (v1.active == false && v2.active == true)
							{
									v2pos -= cv * (t * lambda/2.0f) * fraction;   	 	 //half energy for edge
							}
							else if (v1.active == true && v2.active == false)
							{
									v1pos -= cv * ((1 - t) * lambda/2.0f) * fraction;	 //half energy
							}
mpos += cv * fraction/2.0f;				   // if half energy for edge so must leav half energy to m 	  

About mass, ofcouse if mass different , collision will effect diferently for that objects

float c=1/(obj1.invmass+obj2.invmass);
obj1.vec -= obj1.invmass*c/2*collision_vector;
obj2.vec += obj1.invmass*c/2*collision_vector;
//invmas=1/mass;

hmm wrote an answer but it disapeard .
ok I will answer again
I think maybe your problem is in two places , try to rewrite these places with code below
maybe this helps...

if (v1.active == true && v2.active == true)
							{
									v1pos -= cv * ((1 - t) * lambda / 2.0f) * fraction;   //   (1-t)/2
									v2pos -= cv * (t * lambda / 2.0f) * fraction;	 	 //	 t/2		   ( t+(1-t))/2=1/2   half energy for edge
						    }
							else if (v1.active == false && v2.active == true)
							{
									v2pos -= cv * (t * lambda/2.0f) * fraction;   	 	 //half energy for edge
						    }
							else if (v1.active == true && v2.active == false)
							{
									v1pos -= cv * ((1 - t) * lambda/2.0f) * fraction;	 //half energy
						    }
mpos += cv * fraction/2.0f;				   // if half energy for edge so must leav half energy to m 	   

About mass, ofcouse if mass different , collision will effect diferently for that objects

float c=0.5f/(obj1.invmass+obj2.invmass);
obj1.vec -= obj1.invmass*c ......
obj2.vec += obj1.invmass*c .....
invmas=1/mass;

hmm wrote an answer but it disapeard .
ok I will answer again
I think maybe your problem is in two places , try to rewrite these places with code below
maybe this helps...

if (v1.active == true && v2.active == true)
						    {
								    v1pos -= cv * ((1 - t) * lambda / 2.0f) * fraction;
								    v2pos -= cv * (t * lambda / 2.0f) * fraction;
	 	 	 	 	 	 	 mpos += cv * fraction/2.0f;
						    }
						    else if (v1.active == false && v2.active == true)
						    {
								    v2pos -= cv * (t * lambda) * fraction;
	 	 	 	 	 	 	 mpos += cv * fraction;
						    }
						    else if (v1.active == true && v2.active == false)
						    {
								    v1pos -= cv * ((1 - t) * lambda) * fraction;
	 	 	 	 	 	 	 mpos += cv * fraction;
						    }
						    

About mass, ofcouse if mass different , collision will effect diferently for that objects

float c=0.5f/(obj1.invmass+obj2.invmass);
obj1.vec -= obj1.invmass*c ......
obj2.vec += obj1.invmass*c .....
invmas=1/mass;