  We study numerically the structure of a vortex lattice in two-component
Bose-Einstein condensates with equal atomic masses and equal intra- and
inter-component coupling strengths. The numerical simulations of the
Gross-Pitaevskii equation show that the quantized vortices form uncertain
lattice configurations accompanying the vortex stripes, honeycomb lattices, and
their complexes. This is a result of the degeneracy of the system for the SU(2)
symmetric operation, which makes a continuous transformation between the above
structures. In terms of the pseudospin representation, the complex lattice
structures are identified to a hexagonal lattice of doubly-winding
half-skyrmions.
