To overcome the limited scan range of existing beam-scanning antennas and the dependence of circularly polarized scanning schemes on circularly polarized feeds, a dual-circularly polarized wide-angle dual-beam scanning transmitarray antenna excited by linear polarization is proposed. The transmitarray is constructed from spin-decoupled regular-hexagonal receiver-transmitter unit cells arranged in a honeycomb lattice. This lattice supports denser element packing than a conventional square lattice and helps maintain good angular stability under oblique incidence. Under linearly polarized excitation, the unit cells independently tailor the phases of the left- and right-handed circularly polarized (LCP and RCP) transmitted waves, allowing two orthogonal circularly polarized beams to be generated and steered independently within a single aperture. Beam scanning is realized by changing the feed position, and a coordinate-ascent-based phase compensation strategy is further developed to jointly synthesize the phase distributions required for different feed positions, yielding a complete transmitarray design procedure. The LCP and RCP target phases are then mapped to the initial phase and the rotation angle of each unit cell, enabling decoupled control of the two circularly polarized beams. Simulated and measured results show that, around 20 GHz, the proposed antenna achieves LCP beam scanning from -55° to 0° and RCP beam scanning from 0° to 55°, corresponding to an overall scanning range of 110°. Within this range, the measured scan loss is below 3.2 dB, the maximum realized gain reaches 20.3 dBic, the sidelobe levels remain below -11.5 dB, and the peak aperture efficiency is 37%. In addition, for all feed excitations, the axial ratios of both beams in their main-beam directions remain below 3 dB from 19 to 21 GHz, confirming good circular-polarization purity throughout the scanning process. The proposed design provides a low-profile and low-complexity solution for wide-angle dual-circularly polarized beam scanning and is promising for satellite communications, target tracking, and polarization-robust wireless links.