In my opinion, I think there is no contradiction et all. But 1st let's solve some name issues as per logic as we are talking about higher beings viz the Tridevs who are beyond Kalpas.
- 100 years of Brahma = 1 Maha Kalpa (MK).
By following, this naming pattern, let's say.:
- 100 years of Vishnu = 1 Para Kalpa (PK).
- 100 years of Rudra = 1 Parat Para Kalpa (PPK).
- 1 breath of Sada Shiva = 1 Tat Parat Para Kalpa (TK).
As, I have discussed in this answer of mine. After 100 yrs Brahma merges into Vishnu, then Vishnu into Rudra after his 100 yrs and Rudra into Prakriti after becoming Nara and completing his 100 yrs which is equal to just a breath of SadaShiva. And Sada Shiva is undecaying and the count of his breaths are uncountable, infinite and unpredictable.
As, I have discussed in this answer of mine that it's actually the same Brahma who takes birth again and again as a newborn. Also, the names given to each Brahma are the names of Brahma only like Vrinchi, Chaturmukha, etc etc. So, it should be same in case of Vishnu and Rudra also.
Sri Shiva Purana 1.10.:
Bhagawan Shiva says to Brahma and Vishnu.:
9. In order to look after these five-fold activities (pañcakṛtya) I have five faces, four in the four quarters and the fifth in the middle.
10. O sons, in view of your austerities you two have received the first two activities:—creation and maintenance. You have gratified me and are blessed therefore.
11. Similarly, the other two activities (annihilation and concealment) have been assigned to Rudra and Maheśa. The fifth one of Anugraha (liberation) cannot be taken up by any other.
12. All this previous arrangement has been forgotten by both of you due to lapse of time, not so by Rudra and Maheśa.
13. I have assigned them my equality in form, dress, activity, vehicle, seat, weapons etc.
14. O dear sons, your delusion was the result of your not meditating upon me. If you had retained my knowledge you would not have embibed this false pride of being Maheśa yourselves.
15. Hence, hereafter, both of you shall start reciting the mantra Oṃkāra to acquire knowledge of me. It shall quell your false pride as well.
16. I have taught this great auspicious mantra. Oṃkāra came out of my mouth. Originally it indicated me.
17. It is the indicator and I am the indicated. This mantra is identical with me. The repetition of this mantra is verily my repeated remembrance.
As for this contradiction about the life span of Tridevs, my best logic is each Breath of SadaShiva is not same in lenght and is unpredictable. Plus, the occurrence of the life span of Tridevs varies in Shiva Purana only as you can see from both mine and your answer. It's because they are from different TK. The proof is that both the Lingodhbhava and Daksha Yagna episodes varies in Srishti Khanda and Vayu Khanda. So, different TK same with Skanda Purana i guess.
Rig Veda Khilani SSS.:
परात्परतरो ब्रह्मा तत्परात्परतो हरिः ।
तत्परात्परतो ईश तन्मे मन शिवसंकल्पमस्तु ।। 18 ।।
Greater than the great is Brahma, greater still than that great one is Hari, even greater than this one is Ishana. May my mind always remains full of Auspicious Shiva thoughts.
I hope this clarifies your queries.