Whilst incorporating new material, Testamentum Domini strictly follows the order of Traditio apostolica as a source. It may expand, abbreviate or substitute, but the pattern of the original is manifest.
With one exception. Chapters 36-39 in Traditio apostolica read:
36: Every faithful one should be concerned that, before he consumes anything else, he partake in the eucharist. For if he partakes in faith, even if anything deadly is given him, after that it shall not overcome him.
37: Everybody should be concerned that one who is not of the faithful, nor a mouse nor any other animal, should eat of the eucharist, and that none of it should fall and be altogether lost. For it is the body of Christ to be eaten by the faithful, and not to be despised. 38: For, blessing the cup in the name of God, you received, as it were, the antitype of the blood of Christ. For this reason do not pour it out, that no alien spirit might lick it up because you despised it; you shall be guilty of the blood, like one who despises the price with which he has been bought.
39: The deacons and the presbyters should gather daily at the place which the bishop appoints for them. Let the deacons not fail to assemble at all times, unless illness prevents them. 2When all have gathered together, they should teach those who are in the church, and in this way, when they have prayed, each should go to the task which falls to him.
This is within the “longer ending”.
37 and 39 are omitted entirely by Testamentum Domini. This should not cause overmuch alarm as, in particular without chapter divisions, this might simply count as abbreviation. However, what is most odd is that 38 is included out of sequence earlier in the document, in material otherwise derived from Traditio apostolica 22, and 36 is found, again out of sequence, towards the end in the midst of material otherwise parallel to chapter 43.
Who can explore this strange design?
Offers, anyone? Anyone? I would suggest a mislocated page, but this would only account for one displacement, and not the other.