Are Pei Xingjian and Di Renjie from the same era?

Yes. Pei Xingjian and Di Renjie were of the same generation. Pei Xingjian was a famous general, politician and calligrapher in the Tang Dynasty. He died in the first year of Yongchun (682). Di Renjie was a politician in the Tang Dynasty and Wu Zhou Dynasty. He died in the first year of Jiushi (700). Both of them were officials during the Li Zhi period of Emperor Gaozong of the Tang Dynasty and were from the same era.