Is “Regarding the number of troops that defeated Yao Hai when the imperial army attacked Li Shidao, the two histories record different numbers.” true?

The Old Book of Tang, in the biographies of Yu Di, Han Hong, and Wang Zhixing, records that Li Shidao ordered Yao Hai to lead 20,000 troops to besiege Feng: “The rebels again ordered Yao Hai to lead elite troops of 20,000 to besiege Feng, and the attack on the city was very urgent. Zhixing again defeated them.” However, the New Book of Tang, in the biographies of Yu, Wang, Du, and Fan, records Yao Hai's troops as 50,000: “He advanced and defeated Yao Hai's 50,000 troops north of Feng, capturing three beautiful concubines. Zhixing said: 'If there are women in the army, how can it not be defeated?' He immediately beheaded them as a warning.” The numbers in the two histories differ.