Does the above sentence mean that the same God is not identified as "Indra" in every manvantara?
Indra is a position and occupied by different people at various times. Please see Narada purana for the list of manvantaras and the indra of each manvantara.
“I will first tell you about the manvantaras,” replied Sudharma.
There are fourteen such eras in one of Brahma’s days. Each such era is ruled over by a Manu. And the gods also change from one manvantara to another. In addition, the title of Indra changes hands.
The first Manu was Svayambhuva. The gods were then the yamas and the Indra was Shachipati.,
The second Manu was Svarochisha. The gods were the paravatas and tushitas and the Indra was Vipashchita.
The third Manu was Uttama. The gods were the sudhamas, satyas, shivas and pratardanas and the Indra was Sushanti.
The fourth Manu was Tamasa. The gods were the surupas, haris, suptas and sudhis and the Indra was Shibi.
The fifth Manu was Raivata. The gods were the amitabhas and the Indra was Ribhu
The sixth Manu was Chakshusha. The gods were the adyas and the Indra was Manojava.
The seventh manu was Vaivasvata. This is the manvantara that is now current. The gods are the adityas, vasus and rudras and the Indra is Purandara.
There will be seven more manvantaras before the destruction.
The eighth Manu will Suryasavarni. The gods will be the sutapas and the Indra will be Vali.
The ninth manu will be Dakshasavarni. The gods will be the paravatas and the Indra will be Adbhuta.
The tenth manu will be Brahmasavarni. The gods will be the vamanas and the Indra will be Shanti.
The eleventh Manu will be Dharmasavarni. The gods will be the vihangamas and the Indra will be Vrisha.
The twelfth manu will be Rudrasavarni. The gods will be the haritas and the Indra will be Ritadhama.
The thirteenth Manu will be Rouchya. The gods will be the sutramas and the Indra will be Divaspati.
The fourteenth Manu will be Bhoutya. The gods will be the chakshushas and the Indra will be Shuchi.