Governors at Broomfield College, one of the five colleges initially showing a strong interest in linking up with Derby University to form a new region-wide institution have ruled out a move towards formal union.
And governors at Derby College, Wilmorton, which has opted to keep its options open throughout the merger talks, have also voted to reject the idea of a single legal entity.
Both have agreed only to go as far as exploring routes towards greater collaboration on the curriculum and other issues.
Meanwhile, the four other colleges in at the start of the scheme have left the way open to investigate the possibility of merger, which would need approval from the further and higher education funding bodies.
Governors at Mackworth, High Peak, South East Derbyshire and Burton-on-Trent colleges have pledged to provide a unified system of post-school education and training in the region. However, that leaves options open either for full merger or for some form of network in which each institution would remain a separate entity.
The university is aiming for a direct merger, creating a 50,000-student institution offering a ladder of awards.
Alan Harrison, principal of Mackworth College, Derby, denied the colleges, who took the first initiative and approached the university, had got cold feet. He said: "I think people are at different points on a continuum. Some are keener to consider a straight merger and others a framework. All the options are open for us."
However, Broomfield principal Clark Field said no one was "really able to describe what a full legal merger would look like". He said: "It could be quite a considerable undertaking and could require legislation. Until it has been tested out and our organisation knows what it would have to be working towards it is difficult to commit ourselves."
David Croll, principal of Derby College, Wilmorton, said: "Governors feel strongly that the college has an important function in providing choice and that would be removed if a single merged organisation came about."
However, there was a strong feeling that an agreed curriculum framework would benefit colleges, universities and students, he said.
Mike Taylor, principal of High Peak College, Buxton, which resolved this week to look towards full merger, said: "At the stage we are at I can understand people wanting to know more about what it will be before signing up to something."