Japt, 15 19 bytes

ã cUã)à f_¬¥UÃâ ®®n

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ã                  - substrings of input
  cUã)             - concatenated to substrings of input(repeated)
      à            - combinations
        f_´U      - take combinatons if == input when joined
             Ãâ    - implicitly returns unique elements

• Added ®®n to convert results to numbers thus removing leading zeroes.

Japt, 18 bytes

ã
cU à f_¬¥NîmnÃâ

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• Saved 1 thanks to @Shaggy !

    ã                  - substrings of input
      cUã)             - concatenated to substrings of input(repeated)
          à            - combinations
            f_´N      - take combinatons if == input when joined
           ®mn  - deduplicates ( @Shaggy ® )
                    Ãâ    - implicitly returns unique elements

Japt, 15 bytes

ã cUã)à f_¬¥UÃâ

Try it

    ã                  - substrings of input
      cUã)             - concatenated to substrings of input(repeated)
          à            - combinations
            f_´U      - take combinatons if == input when joined
                 Ãâ    - implicitly returns unique elements

Japt, 15 19 bytes

ã cUã)à f_¬¥UÃâ ®®n

Try it

ã                  - substrings of input
  cUã)             - concatenated to substrings of input(repeated)
      à            - combinations
        f_´U      - take combinatons if == input when joined
             Ãâ    - implicitly returns unique elements

• Added ®®n to convert results to numbers thus removing leading zeroes.