Is it possible to attach the sheet-type filter for the SIGMA 14mm F1.4 DG DN | Art to the SIGMA 14mm F1.8 DG HSM | Art for DSLR cameras?

No. The SIGMA 14mm F1.4 DG DN | Art has a different shaped filter holder than the SIGMA 14mm F1.8 DG HSM | Art (FHR-11 for Canon EF mount). The sheet filter cannot be shared.