Are fragments with the same number of base pairs always the same exact fragment?

No, the fragments with same number of base pairs  do not always the same exact fragments.

Lets take an example, There are two fragments of DNA, having 20 number of base pair each. But the one fragment contains a sequence in which there are 12 GC base pairs.

The second fragment contains sequence with only 5 GC pairs.

Hence the same number of base pairs in fragments does not assure Exact fragments.

the oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. this blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. from the left ventricle, the blood passes through the aortic valve to the aorta.

deoxygenated blood leaves through the right ventricle through the pulmonary artery. from the right atrium, the blood is pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle.