I ran into this bug migrating from 1.7 to 1.8.3 and from 1.8.3 to 1.9.0.

Running "foreman-rake db:migrate" results in:
ActiveRecord::DuplicateMigrationNameError: Multiple migrations have the name AddProvisionMethodToHosts
/usr/share/foreman/vendor/ruby/1.9.1/gems/activerecord-3.2.21/lib/active_record/migration.rb:637:in `block in migrations'
/usr/share/foreman/vendor/ruby/1.9.1/gems/activerecord-3.2.21/lib/active_record/migration.rb:629:in `map'
....

The Fix:
mv /usr/share/foreman/db/migrate/20140304184854_add_provision_method_to_hosts.rb /usr/share/foreman/db/migrate/20141204184854_add_provision_method_to_hosts.rb

More Details:
https://groups.google.com/forum/#!topic/foreman-users/2nAj8qEu_5o

Host Details:
cat /etc/debian_version
7.8
cat /etc/apt/sources.list.d/foreman.list
#deb http://deb.theforeman.org/ wheezy stable
deb http://deb.theforeman.org/ wheezy 1.9
deb http://deb.theforeman.org/ plugins 1.9

dpkg --list | grep foreman
ii foreman 1.9.0-1 amd64 Systems management web interface
ii foreman-cli 1.9.0-1 all metapackage providing hammer CLI for Foreman
ii foreman-compute 1.9.0-1 all metapackage providing fog dependencies for Foreman,
ii foreman-console 1.9.0-1 all metapackage providing console dependencies for Foreman
ii foreman-ec2 1.9.0-1 all metapackage providing EC2 dependencies for Foreman
ii foreman-installer 1.9.0-1 all Automated puppet-based installer for The Foreman
ii foreman-libvirt 1.9.0-1 all metapackage providing libvirt dependencies for Foreman
ii foreman-mysql 1.3.0-2 all metapackage providing MySQL dependencies for Foreman
ii foreman-postgresql 1.9.0-1 all metapackage providing PostgreSQL dependencies for Foreman
ii foreman-proxy 1.9.0-1 all RESTful proxies for DNS, DHCP, TFTP, and Puppet
ii foreman-sqlite3 1.9.0-1 all metapackage providing sqlite dependencies for Foreman
ii foreman-vmware 1.9.0-1 all metapackage providing vmware dependencies for Foreman
ii ruby-foreman-deface 0.9.1-2 all Foreman Deface Plugin Dependency
ii ruby-foreman-setup 3.0.2 all Foreman Setup Plugin
ii ruby-hammer-cli-foreman 0.3.0-1 all Foreman commands for Hammer

Full Error Output:
foreman-rake db:migrate
rake aborted!
ActiveRecord::DuplicateMigrationNameError: Multiple migrations have the name AddProvisionMethodToHosts
/usr/share/foreman/vendor/ruby/1.9.1/gems/activerecord-3.2.21/lib/active_record/migration.rb:637:in `block in migrations'
/usr/share/foreman/vendor/ruby/1.9.1/gems/activerecord-3.2.21/lib/active_record/migration.rb:629:in `map'
/usr/share/foreman/vendor/ruby/1.9.1/gems/activerecord-3.2.21/lib/active_record/migration.rb:629:in `migrations'
/usr/share/foreman/vendor/ruby/1.9.1/gems/activerecord-3.2.21/lib/active_record/migration.rb:734:in `migrations'
/usr/share/foreman/vendor/ruby/1.9.1/gems/activerecord-3.2.21/lib/active_record/migration.rb:741:in `pending_migrations'
/usr/share/foreman/app/services/foreman/plugin.rb:221:in `pending_migrations'
/usr/share/foreman/app/services/foreman/plugin.rb:199:in `permission'
/usr/share/foreman/vendor/ruby/1.9.1/gems/foreman_setup-3.0.2/lib/foreman_setup/engine.rb:25:in `block (3 levels) in <class:Engine>'
/usr/share/foreman/app/services/foreman/plugin.rb:190:in `instance_eval'
/usr/share/foreman/app/services/foreman/plugin.rb:190:in `security_block'
/usr/share/foreman/vendor/ruby/1.9.1/gems/foreman_setup-3.0.2/lib/foreman_setup/engine.rb:24:in `block (2 levels) in <class:Engine>'
/usr/share/foreman/app/services/foreman/plugin.rb:64:in `instance_eval'
/usr/share/foreman/app/services/foreman/plugin.rb:64:in `register'
/usr/share/foreman/vendor/ruby/1.9.1/gems/foreman_setup-3.0.2/lib/foreman_setup/engine.rb:16:in `block in <class:Engine>'
/usr/share/foreman/vendor/ruby/1.9.1/gems/railties-3.2.21/lib/rails/initializable.rb:30:in `instance_exec'
/usr/share/foreman/vendor/ruby/1.9.1/gems/railties-3.2.21/lib/rails/initializable.rb:30:in `run'
/usr/share/foreman/vendor/ruby/1.9.1/gems/railties-3.2.21/lib/rails/initializable.rb:55:in `block in run_initializers'
/usr/share/foreman/vendor/ruby/1.9.1/gems/railties-3.2.21/lib/rails/initializable.rb:54:in `each'
/usr/share/foreman/vendor/ruby/1.9.1/gems/railties-3.2.21/lib/rails/initializable.rb:54:in `run_initializers'
/usr/share/foreman/vendor/ruby/1.9.1/gems/railties-3.2.21/lib/rails/application.rb:136:in `initialize!'
/usr/share/foreman/vendor/ruby/1.9.1/gems/railties-3.2.21/lib/rails/railtie/configurable.rb:30:in `method_missing'
/usr/share/foreman/config/environment.rb:5:in `<top (required)>'
/usr/share/foreman/vendor/ruby/1.9.1/gems/polyglot-0.3.5/lib/polyglot.rb:65:in `require'
/usr/share/foreman/vendor/ruby/1.9.1/gems/polyglot-0.3.5/lib/polyglot.rb:65:in `require'
/usr/share/foreman/vendor/ruby/1.9.1/gems/activesupport-3.2.21/lib/active_support/dependencies.rb:251:in `block in require'
/usr/share/foreman/vendor/ruby/1.9.1/gems/activesupport-3.2.21/lib/active_support/dependencies.rb:236:in `load_dependency'
/usr/share/foreman/vendor/ruby/1.9.1/gems/activesupport-3.2.21/lib/active_support/dependencies.rb:251:in `require'
/usr/share/foreman/vendor/ruby/1.9.1/gems/railties-3.2.21/lib/rails/application.rb:103:in `require_environment!'
/usr/share/foreman/vendor/ruby/1.9.1/gems/railties-3.2.21/lib/rails/application.rb:305:in `block (2 levels) in initialize_tasks'
Tasks: TOP => db:migrate => environment
(See full trace by running task with --trace)