Please refer to the DeepStream documentation:
NvDCF can generate a unique ID to some extent. If enabled by setting
useUniqueID: 1 , NvDCF would generate a 32-bit random number at the initialization stage and use it as the upper 32-bit of the following target ID generation, which is uint64_t type. The randomly generated upper 32-bit number allows the target ID to increment from a random position in the possible ID space. The initial value of the lower 32-bit of the target ID starts from 0. If disabled (which is the default value), the target ID generation would be incremented from 0.
So, if you take only the lower 32-bit of the ID, then you can get simple ID. Or, you can set
useUniqueID: 0 to disable unique ID feature, generating IDs from 0.