伯仲
はくちゅう being evenly matched; being equal with
Why it means this
伯 (the eldest brother) + 仲 (the second brother) — 'eldest and second son', so close in age and ability there's little to choose between them; neck and neck (実力伯仲; 与野党伯仲).
Breakdown
Each character links to its full entry — origin story, stroke order, and readings.