Hi Viktorie
the only place I can see them being synonymised is here:
http://nhm2.uio.no/botanisk/sopp/tax-list/tax-asco.htm
whether that is because they were viewed as true synonyms, or by a misintepretation of a re-determination (your very problem) I don't know. I can see no other place where they are synonymised.
Hopefully someone who knows both fungi might be able to clarify the situation.

best wishes
Chris

In the 1971 Dennis [Kew Bulletin 25 (2): 341. 1971] noted that Octospora pleurozii Ekbl. Seems similar at Aleuria cestrica (Ellis & Everh.)Seaver [North American Cup Fungi (Operculates): 98. 1928; based on Peziza cestrica Ellis & Everh., J. Mycol. 1 (12): 152 (1885)] but with slightly larger ascospores and a less reticulate ornament. In same way, Moravcec write: "It is interesting that Octospora pleurozii has very similar spore-ornamentation and also some other features, which, in my opinion, suggests affinity to Aleuria or that it could even be identical with A. bicucullata" [Ceska Mykologie 26 (2): 77.1972; see also Ceska Mykologie 34 (4): 218. 1980].
Aleuria bicucullata sensu Moravcec is now considered a synonyms of Aleuria congrex (P. Karsten)Svreck [Ceska Mykologie 35 (1): 23. 1981; based on Peziza congrex P. Karst. In Thümen, Mycoth. Univ.: n. 717. 1885]. Haffner write, in his revisione of the genus Aleuria: "...warum Moravec (1972) und andere nach ihm (siehe A. congrex) Aufsammlungen von A. congrex zu A. bicucullata stellen...Octospora pleurozii Eckbl. ist bei A. congrex einzourdnen, nicht bei A. cucullata" [Rheinl.-Pfalz. Pilkj. 3: 17. 1993].

Thank you both, I didn't know about this article by Dennis.

Mr. Yates: yes, this is the page I found and exactly what I meant.