We fixed this issue today. The fix is available in beta here: https://www.skipper18.com/support/402/downloads-skipper-beta
Here is our testing sample for 119, 120 and 121 characters:
<?php
use Doctrine\ORM\Mapping as ORM;
/**
 * @ORM\Entity
 */
class Entity2
{
    /**
     * @ORM\Column(type="string", length=255, nullable=true, name="contract_type_h", options={"collation":"ascii_bin"})
     */
    private $t120;
    /**
     * @ORM\Column(
     *     type="string",
     *     length=255,
     *     nullable=true,
     *     name="contract_type_ha",
     *     options={"collation":"ascii_bin"}
     * )
     */
    private $t121;
    /**
     * @ORM\Column(type="string", length=255, nullable=true, name="contract_type_", options={"collation":"ascii_bin"})
     */
    private $t119;
}