Solution 1:

move:   inc     r6              ;For avoiding 255 loop if is 0 the value
        inc     r7
and after that:
        mov     a,dpl           ;Origin is lower than destination
        add     a,r7            ;We add the number of bytes to the origin
        mov     sum_l,a         ;And we check if overlaps with destination
        mov     a,dph
        addc    a,r6
        mov     sum_h,a

But r6:r7 are no longer the number of bytes!

And also:

up:     djnz    r7,up1
        djnz    r6,up1
        ret
up1:    movx    a,@dptr          ;We move the data in up direction
        inc     dptr
        mov     store,r4         ;Swap r4,dph
        mov     r4,dph
        mov     dph,store
        mov     store,r5         ;Meant to swap r5,dpl I guess
        mov     r4,dpl
        mov     dpl,r5
        movx    @dptr,a
        inc     dptr
        sjmp    up

This moves one byte from destination to source end the next from source to destination (if the swapping was done correctly)!

Solution 2:

   mov   a,r4        ;now determine copy direction 
   cjne  a,dph,BlkMovX2
   mov   a,r5 
   cjne  a,dpl,BlkMovX2
BlkMovX2:
   jnc   BlkMovDwn
BlkMovUp:           ;----------- LDIR -------------
   mov   P2,r4       ;prepare destination address for movx @r0,a
;   mov   r0,ar5
   mov   r0,a         ;!trick - a already contains r5

If dph != r4 then a == r4, not r5!

Solution 3:

normalmove:
      mov a,r7
      orl a,r6
      jz  done
      dec r7
      jnz mv10
      dec r6

Decrementing r7 does not affect the "zero flag"!

Now you may guess where my vote went.