According to this, they are the same:
The shift arithmetic left (SAL) and shift logical left (SHL)
instructions perform the same operation; they shift the bits in the
destination operand to the left (toward more significant bit
locations). For each shift count, the most significant bit of the
destination operand is shifted into the CF flag, and the least
significant bit is cleared (see Figure 7-7 in the Intel®64 and IA-32
Architectures Software Developer’sManual, Volume 1).
Both were probably included just for completeness since there is a distinction for right-shifts.